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{
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                "id": "CVE-2026-116469",
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                "timestamp": "2026-10-26T13:32:47.760705Z",
                "version": "2.0.3"
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          "dateUpdated": "2026-10-26T14:35:18.399Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "cpes": [
            "cpe:2.3:a:misp:misp-guard:*:*:*:*:*:*:*:*"
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          "modules": [
            "src/mispguard.py"
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          "product": "misp-guard",
          "programFiles": [
            "src/mispguard.py"
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          "repo": "https://github.com/MISP/misp-guard",
          "vendor": "MISP",
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          "type": "remediation developer",
          "value": "Luciano Righetti"
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          "value": "Claude Opus 5.5 (1M context)"
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      ],
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          "lang": "en",
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              "value": "\u003cp\u003eMISP Guard, a proxy-based security filter for MISP (Malware Information Sharing Platform) feed distribution, contains a case-sensitivity flaw in multiple policy enforcement checks. The functions check_required_taxonomy_exists, check_required_taxonomy_tags_allowed, check_blocked_attribute_categories, and check_blocked_analyst_data_sharing_groups_uuids performed case-sensitive string comparisons when matching event tags, attribute categories, and sharing-group UUIDs against configured allow/block lists.\u003c/p\u003e\u003cp\u003eAn attacker with the ability to create or modify events in a MISP instance (or a connected instance that pushes events through the guard) could craft events using different letter case in taxonomy tag names, attribute categories, or sharing-group UUIDs to bypass the configured security policies. For example, if the policy requires the \u0027tlp\u0027 taxonomy with only \u0027tlp:clear\u0027 allowed, an event tagged \u0027TLP:AMBER\u0027 would not be recognized as belonging to the \u0027tlp\u0027 taxonomy and would therefore not be checked against the allowed-tags list, resulting in the event being forwarded to feed consumers. Similarly, a blocked attribute category such as \u0027Person\u0027 would not match a configured block entry of \u0027person\u0027, allowing the attribute to pass through the filter.\u003c/p\u003e\u003cp\u003eThe security impact is unauthorized disclosure of threat-intelligence data that the operator intended to restrict. Events carrying non-allowed TLP (Traffic Light Protocol) markings, blocked attribute categories, or blocked sharing-group associations are forwarded to downstream feed consumers in violation of the configured distribution policy. This undermines the confidentiality controls that MISP Guard is designed to enforce.\u003c/p\u003e\u003cp\u003eThe vulnerability is trivially exploitable: the attacker only needs to alter the letter case of a tag, category, or UUID string. No authentication beyond normal MISP event-creation privileges is required, and no user interaction is needed.\u003c/p\u003e"
            }
          ],
          "value": "MISP Guard, a proxy-based security filter for MISP (Malware Information Sharing Platform) feed distribution, contains a case-sensitivity flaw in multiple policy enforcement checks. The functions check_required_taxonomy_exists, check_required_taxonomy_tags_allowed, check_blocked_attribute_categories, and check_blocked_analyst_data_sharing_groups_uuids performed case-sensitive string comparisons when matching event tags, attribute categories, and sharing-group UUIDs against configured allow/block lists.\n\nAn attacker with the ability to create or modify events in a MISP instance (or a connected instance that pushes events through the guard) could craft events using different letter case in taxonomy tag names, attribute categories, or sharing-group UUIDs to bypass the configured security policies. For example, if the policy requires the \u0027tlp\u0027 taxonomy with only \u0027tlp:clear\u0027 allowed, an event tagged \u0027TLP:AMBER\u0027 would not be recognized as belonging to the \u0027tlp\u0027 taxonomy and would therefore not be checked against the allowed-tags list, resulting in the event being forwarded to feed consumers. Similarly, a blocked attribute category such as \u0027Person\u0027 would not match a configured block entry of \u0027person\u0027, allowing the attribute to pass through the filter.\n\nThe security impact is unauthorized disclosure of threat-intelligence data that the operator intended to restrict. Events carrying non-allowed TLP (Traffic Light Protocol) markings, blocked attribute categories, or blocked sharing-group associations are forwarded to downstream feed consumers in violation of the configured distribution policy. This undermines the confidentiality controls that MISP Guard is designed to enforce.\n\nThe vulnerability is trivially exploitable: the attacker only needs to alter the letter case of a tag, category, or UUID string. No authentication beyond normal MISP event-creation privileges is required, and no user interaction is needed."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-10",
          "descriptions": [
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              "value": "CAPEC-10 Parameter Tampering"
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        }
      ],
      "metrics": [
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            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
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            "vulnIntegrityImpact": "NONE",
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              "cweId": "CWE-178",
              "description": "CWE-178 Improper Handling of Case Sensitivity",
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              "type": "CWE"
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              "description": "CWE-20 Improper Input Validation",
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          "name": "Security patch",
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          "url": "https://github.com/MISP/misp-guard/commit/9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c"
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              "value": "\u003cp\u003eThe fix makes all policy-matching comparisons case-insensitive by applying .lower() to both the input value (tag name, attribute category, sharing-group UUID) and the configured policy value (required taxonomy prefix, allowed tags, blocked categories, blocked UUIDs) before performing the comparison. This ensures that a tag such as \u0027TLP:AMBER\u0027 is correctly recognized as belonging to the \u0027tlp\u0027 taxonomy and is checked against the allowed-tags list, and that a blocked category or UUID is matched regardless of letter case.\u003c/p\u003e"
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          "value": "The fix makes all policy-matching comparisons case-insensitive by applying .lower() to both the input value (tag name, attribute category, sharing-group UUID) and the configured policy value (required taxonomy prefix, allowed tags, blocked categories, blocked UUIDs) before performing the comparison. This ensures that a tag such as \u0027TLP:AMBER\u0027 is correctly recognized as belonging to the \u0027tlp\u0027 taxonomy and is checked against the allowed-tags list, and that a blocked category or UUID is matched regardless of letter case."
        }
      ],
      "title": "MISP Guard Case-Sensitive Policy Bypass Allows Unauthorized Feed Data Forwarding",
      "x_gcve": [
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              "x_patch2vuln": {
                "assumptions": [
                  "The MISP Guard is assumed to operate as a proxy filtering outbound MISP feed data; the attacker is assumed to have the ability to create or modify events in a MISP instance that feeds through the guard. The patch does not specify the exact deployment topology.",
                  "PR:L assumes that creating events in MISP requires at least a low-privilege authenticated account. If the guard is used in a context where events are pushed from a connected MISP instance without per-event authentication, PR could be None.",
                  "The CAPEC-10 mapping is the closest available pattern; the actual attack involves modifying structured JSON event fields rather than traditional HTTP parameters, so the mapping is approximate.",
                  "No specific affected or fixed version numbers are provided in the patch metadata; the version range is marked as unspecified.",
                  "The commit message references \u0027ID 004\u0027 as a prior related fix, suggesting this is a follow-up to an earlier incomplete case-sensitivity fix, but no further details about that prior fix are available in the patch."
                ],
                "capecRationale": [
                  {
                    "capecId": "CAPEC-10",
                    "rationale": "The attacker tampers with the letter case of tag names, attribute categories, or sharing-group UUIDs in MISP events to bypass the guard\u0027s policy checks. This is a form of parameter tampering where the input is modified in a way that the validation logic does not anticipate. CAPEC-10 is the closest available pattern; the uncertainty is that the tampering occurs in structured event data rather than in a traditional request parameter, but the underlying technique (modifying input to evade validation) aligns with this pattern."
                  }
                ],
                "commit": "9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c",
                "confidence": "medium",
                "credits": [
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                    "lang": "en",
                    "type": "remediation developer",
                    "value": "Luciano Righetti"
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                ],
                "cvssRationale": "AV:N: The MISP feed is consumed over the network (HTTP). AC:L: Exploitation requires only changing the letter case of a tag, category, or UUID string. AT:N: No log or audit tampering is needed. PR:L: The attacker needs the ability to create or modify events in a MISP instance, which typically requires a low-privilege user account or a connected instance. UI:N: No user interaction is required. VC:H: The primary impact is unauthorized disclosure of data that the operator intended to restrict (non-allowed TLP tags, blocked categories, blocked sharing groups are forwarded to feed consumers). VI:N: The data content is not modified, only improperly shared. VA:N: No availability impact. SC/SI/SA:N: No secondary system impact is evidenced.",
                "fixSummary": "The fix makes all policy-matching comparisons case-insensitive by applying .lower() to both the input value (tag name, attribute category, sharing-group UUID) and the configured policy value (required taxonomy prefix, allowed tags, blocked categories, blocked UUIDs) before performing the comparison. This ensures that a tag such as \u0027TLP:AMBER\u0027 is correctly recognized as belonging to the \u0027tlp\u0027 taxonomy and is checked against the allowed-tags list, and that a blocked category or UUID is matched regardless of letter case.",
                "generatedAt": "2026-10-26T10:33:59.935580Z",
                "generator": "patch2vuln.py",
                "model": "qwen3.8:27b",
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                      "agreementScore": 11,
                      "assumptionCount": 5,
                      "confidence": "medium",
                      "model": "qwen3.8:27b",
                      "score": 7
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                  ],
                  "selectedModel": "qwen3.8:27b",
                  "selectionMethod": "deterministic-consensus-v1",
                  "selectionNotice": "The selected result is closest to model consensus; this heuristic does not establish factual correctness and human review remains required."
                },
                "patchSha256": "26a847175a70394b7c0feaa57f7286f41fb131fc28c4c540412e88018c749628",
                "patchSummary": "In src/mispguard.py, four comparison sites were changed: (1) check_required_taxonomy_exists now uses tag[\u0027name\u0027].lower().startswith(required_taxonomy.lower() + \u0027:\u0027) instead of a case-sensitive startswith; (2) check_required_taxonomy_tags_allowed applies .lower() to both the tag name and the required taxonomy prefix in the startswith check; (3) check_blocked_attribute_categories compares attribute[\u0027category\u0027].lower() against a lowercased list of blocked categories; (4) check_blocked_analyst_data_sharing_groups_uuids compares the UUID in lowercase against a lowercased list of blocked UUIDs. Ninety-one lines of test cases were added to src/test/test_misp_guard.py covering mixed-case TLP tags in required-taxonomy checks and mixed-case blocked attribute categories.",
                "patchTruncated": false,
                "patches": [
                  {
                    "commit": "9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c",
                    "date": "Mon, 26 Oct 2026 10:25:52 +0100",
                    "patchSha256": "26a847175a70394b7c0feaa57f7286f41fb131fc28c4c540412e88018c749628",
                    "source": "https://github.com/MISP/misp-guard/commit/9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c.patch",
                    "sourceUrl": "https://github.com/MISP/misp-guard/commit/9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c.patch",
                    "subject": "fix: [security] match categories and required taxonomies"
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                "source": "https://github.com/MISP/misp-guard/commit/9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c.patch",
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                  "version": "2.0.3"
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                "weaknessRationale": [
                  {
                    "cweId": "CWE-178",
                    "rationale": "The root cause is that string comparisons used to enforce security policies (taxonomy prefix matching, category blocking, UUID blocking) were case-sensitive, allowing an attacker to bypass the checks by altering letter case. CWE-178 is the most specific and accurate mapping."
                  },
                  {
                    "cweId": "CWE-20",
                    "rationale": "More broadly, the guard failed to validate input against the policy in a canonical form, which is a form of improper input validation. CWE-20 is included as a secondary, broader mapping."
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                ]
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            },
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                    "description": "Corrective change authored (9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c): fix: [security] match categories and required taxonomies",
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                    "references": [
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            "cpe:2.3:a:misp:misp-guard:*:*:*:*:*:*:*:*"
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          "type": "remediation developer",
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              "value": "\u003cp\u003eMISP mispguard is a security filtering proxy that inspects and blocks MISP feed responses based on configured rules. The process_feed_response method in src/mispguard.py was responsible for evaluating feed responses before they reached the MISP instance. The original logic only explicitly handled the case where the HTTP status code was not 200 by passing the response through without filtering, on the assumption that non-200 responses would not carry ingestible event data. However, HTTP 2xx status codes other than 200 (such as 201 Created, 203 Non-Authoritative Information, and 206 Partial Content) were also passed through unfiltered. Because MISP may still ingest content from these responses, a malicious or compromised feed host could return a 203 or 206 status code with arbitrary content, effectively bypassing all of mispguard\u0027s filtering rules. This allowed unfiltered or malicious feed data to be ingested into the MISP instance, undermining the security controls that mispguard is designed to enforce. The vulnerability requires the attacker to control or compromise a feed endpoint configured in the MISP instance. No authentication or user interaction is required beyond the feed polling mechanism already in place.\u003c/p\u003e"
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          ],
          "value": "MISP mispguard is a security filtering proxy that inspects and blocks MISP feed responses based on configured rules. The process_feed_response method in src/mispguard.py was responsible for evaluating feed responses before they reached the MISP instance. The original logic only explicitly handled the case where the HTTP status code was not 200 by passing the response through without filtering, on the assumption that non-200 responses would not carry ingestible event data. However, HTTP 2xx status codes other than 200 (such as 201 Created, 203 Non-Authoritative Information, and 206 Partial Content) were also passed through unfiltered. Because MISP may still ingest content from these responses, a malicious or compromised feed host could return a 203 or 206 status code with arbitrary content, effectively bypassing all of mispguard\u0027s filtering rules. This allowed unfiltered or malicious feed data to be ingested into the MISP instance, undermining the security controls that mispguard is designed to enforce. The vulnerability requires the attacker to control or compromise a feed endpoint configured in the MISP instance. No authentication or user interaction is required beyond the feed polling mechanism already in place."
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          "capecId": "CAPEC-2",
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              "value": "CAPEC-2 Input Parameter Manipulation"
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      "metrics": [
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              "value": "\u003cp\u003eThe fix adds an explicit check in process_feed_response that rejects any HTTP response with a status code in the 201-299 range (i.e., successful responses other than 200) by returning a 403 Forbidden response. This ensures that only responses with exactly status code 200 are subject to the normal filtering pipeline, and all other 2xx responses are blocked before they can reach the MISP instance, closing the bypass vector.\u003c/p\u003e"
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        }
      ],
      "title": "MISP mispguard: Feed responses with 2xx status codes other than 200 bypass filtering rules",
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                  "The commit date (26 Oct 2026) is in the future relative to typical analysis timelines; this is taken at face value from the patch metadata."
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      "title": "MISP mispguard: Feed responses with 2xx status codes other than 200 bypass filtering rules",
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                  "The commit date (26 Oct 2026) is in the future relative to typical analysis timelines; this is taken at face value from the patch metadata."
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                  "The CAPEC-10 mapping is the closest available pattern; the actual attack involves modifying structured JSON event fields rather than traditional HTTP parameters, so the mapping is approximate.",
                  "No specific affected or fixed version numbers are provided in the patch metadata; the version range is marked as unspecified.",
                  "The commit message references \u0027ID 004\u0027 as a prior related fix, suggesting this is a follow-up to an earlier incomplete case-sensitivity fix, but no further details about that prior fix are available in the patch."
                ],
                "capecRationale": [
                  {
                    "capecId": "CAPEC-10",
                    "rationale": "The attacker tampers with the letter case of tag names, attribute categories, or sharing-group UUIDs in MISP events to bypass the guard\u0027s policy checks. This is a form of parameter tampering where the input is modified in a way that the validation logic does not anticipate. CAPEC-10 is the closest available pattern; the uncertainty is that the tampering occurs in structured event data rather than in a traditional request parameter, but the underlying technique (modifying input to evade validation) aligns with this pattern."
                  }
                ],
                "commit": "9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c",
                "confidence": "medium",
                "credits": [
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                    "type": "remediation developer",
                    "value": "Luciano Righetti"
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                    "lang": "en",
                    "type": "remediation developer",
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                  },
                  {
                    "lang": "en",
                    "type": "tool",
                    "value": "Claude Opus 5.5 (1M context)"
                  }
                ],
                "cvssRationale": "AV:N: The MISP feed is consumed over the network (HTTP). AC:L: Exploitation requires only changing the letter case of a tag, category, or UUID string. AT:N: No log or audit tampering is needed. PR:L: The attacker needs the ability to create or modify events in a MISP instance, which typically requires a low-privilege user account or a connected instance. UI:N: No user interaction is required. VC:H: The primary impact is unauthorized disclosure of data that the operator intended to restrict (non-allowed TLP tags, blocked categories, blocked sharing groups are forwarded to feed consumers). VI:N: The data content is not modified, only improperly shared. VA:N: No availability impact. SC/SI/SA:N: No secondary system impact is evidenced.",
                "fixSummary": "The fix makes all policy-matching comparisons case-insensitive by applying .lower() to both the input value (tag name, attribute category, sharing-group UUID) and the configured policy value (required taxonomy prefix, allowed tags, blocked categories, blocked UUIDs) before performing the comparison. This ensures that a tag such as \u0027TLP:AMBER\u0027 is correctly recognized as belonging to the \u0027tlp\u0027 taxonomy and is checked against the allowed-tags list, and that a blocked category or UUID is matched regardless of letter case.",
                "generatedAt": "2026-10-26T10:33:59.935580Z",
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                  "selectionNotice": "The selected result is closest to model consensus; this heuristic does not establish factual correctness and human review remains required."
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                "patchSummary": "In src/mispguard.py, four comparison sites were changed: (1) check_required_taxonomy_exists now uses tag[\u0027name\u0027].lower().startswith(required_taxonomy.lower() + \u0027:\u0027) instead of a case-sensitive startswith; (2) check_required_taxonomy_tags_allowed applies .lower() to both the tag name and the required taxonomy prefix in the startswith check; (3) check_blocked_attribute_categories compares attribute[\u0027category\u0027].lower() against a lowercased list of blocked categories; (4) check_blocked_analyst_data_sharing_groups_uuids compares the UUID in lowercase against a lowercased list of blocked UUIDs. Ninety-one lines of test cases were added to src/test/test_misp_guard.py covering mixed-case TLP tags in required-taxonomy checks and mixed-case blocked attribute categories.",
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                "patches": [
                  {
                    "commit": "9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c",
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                    "sourceUrl": "https://github.com/MISP/misp-guard/commit/9868b1d93fc9cc40cc7c69ca11c86afd825bbc1c.patch",
                    "subject": "fix: [security] match categories and required taxonomies"
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                  "role": "Supplier",
                  "timestamp": "2026-10-26T10:33:59Z",
                  "version": "2.0.3"
                },
                "subject": "fix: [security] match categories and required taxonomies",
                "weaknessRationale": [
                  {
                    "cweId": "CWE-178",
                    "rationale": "The root cause is that string comparisons used to enforce security policies (taxonomy prefix matching, category blocking, UUID blocking) were case-sensitive, allowing an attacker to bypass the checks by altering letter case. CWE-178 is the most specific and accurate mapping."
                  },
                  {
                    "cweId": "CWE-20",
                    "rationale": "More broadly, the guard failed to validate input against the policy in a canonical form, which is a form of improper input validation. CWE-20 is included as a secondary, broader mapping."
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    "cveId": "CVE-2026-116469",
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          "product": "misp-guard",
          "programFiles": [
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          "vendor": "MISP",
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              "versionType": "semver"
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      "credits": [
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          "type": "remediation developer",
          "value": "Luciano Righetti"
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        {
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          "type": "remediation developer",
          "value": "Claude Opus 5.5 (1M context)"
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          "supportingMedia": [
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              "value": "\u003cp\u003eMISP mispguard is a security filtering proxy that inspects and blocks MISP feed responses based on configured rules. The process_feed_response method in src/mispguard.py was responsible for evaluating feed responses before they reached the MISP instance. The original logic only explicitly handled the case where the HTTP status code was not 200 by passing the response through without filtering, on the assumption that non-200 responses would not carry ingestible event data. However, HTTP 2xx status codes other than 200 (such as 201 Created, 203 Non-Authoritative Information, and 206 Partial Content) were also passed through unfiltered. Because MISP may still ingest content from these responses, a malicious or compromised feed host could return a 203 or 206 status code with arbitrary content, effectively bypassing all of mispguard\u0027s filtering rules. This allowed unfiltered or malicious feed data to be ingested into the MISP instance, undermining the security controls that mispguard is designed to enforce. The vulnerability requires the attacker to control or compromise a feed endpoint configured in the MISP instance. No authentication or user interaction is required beyond the feed polling mechanism already in place.\u003c/p\u003e"
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          "value": "MISP mispguard is a security filtering proxy that inspects and blocks MISP feed responses based on configured rules. The process_feed_response method in src/mispguard.py was responsible for evaluating feed responses before they reached the MISP instance. The original logic only explicitly handled the case where the HTTP status code was not 200 by passing the response through without filtering, on the assumption that non-200 responses would not carry ingestible event data. However, HTTP 2xx status codes other than 200 (such as 201 Created, 203 Non-Authoritative Information, and 206 Partial Content) were also passed through unfiltered. Because MISP may still ingest content from these responses, a malicious or compromised feed host could return a 203 or 206 status code with arbitrary content, effectively bypassing all of mispguard\u0027s filtering rules. This allowed unfiltered or malicious feed data to be ingested into the MISP instance, undermining the security controls that mispguard is designed to enforce. The vulnerability requires the attacker to control or compromise a feed endpoint configured in the MISP instance. No authentication or user interaction is required beyond the feed polling mechanism already in place."
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      ],
      "impacts": [
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          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-2 Input Parameter Manipulation"
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      "metrics": [
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          "cvssV4_0": {
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            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
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            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
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            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "format": "CVSS",
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              "value": "GENERAL"
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      "problemTypes": [
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          "descriptions": [
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              "type": "CWE"
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      "references": [
        {
          "name": "Security patch",
          "tags": [
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          "url": "https://github.com/MISP/misp-guard/commit/b5f606a4e57a49cc4dbf9b3ef0c6ddd19f866735"
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      "solutions": [
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          "supportingMedia": [
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              "value": "\u003cp\u003eThe fix adds an explicit check in process_feed_response that rejects any HTTP response with a status code in the 201-299 range (i.e., successful responses other than 200) by returning a 403 Forbidden response. This ensures that only responses with exactly status code 200 are subject to the normal filtering pipeline, and all other 2xx responses are blocked before they can reach the MISP instance, closing the bypass vector.\u003c/p\u003e"
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          "value": "The fix adds an explicit check in process_feed_response that rejects any HTTP response with a status code in the 201-299 range (i.e., successful responses other than 200) by returning a 403 Forbidden response. This ensures that only responses with exactly status code 200 are subject to the normal filtering pipeline, and all other 2xx responses are blocked before they can reach the MISP instance, closing the bypass vector."
        }
      ],
      "title": "MISP mispguard: Feed responses with 2xx status codes other than 200 bypass filtering rules",
      "x_gcve": [
        {
          "extensions": {
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                  "description": "Draft vulnerability metadata was generated from a git-format patch using an Ollama-hosted language model. Human validation is required before publication.",
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                  "The assumption that MISP will ingest content from 2xx responses other than 200 is stated in the commit message and code comments but not independently verified; the fix treats this as a security requirement regardless.",
                  "CAPEC-2 (Input Parameter Manipulation) is the closest available pattern; no CAPEC specifically covers HTTP status code manipulation to bypass proxy filtering logic.",
                  "The CVSS vector assumes the attacker controls or compromises a feed endpoint configured in the MISP instance; no additional authentication or network position is assumed beyond that.",
                  "The SSVC technical impact is assessed as \u0027partial\u0027 based on the assumption that the MISP instance remains operational but with degraded filtering; a \u0027total\u0027 impact would require evidence of data corruption or system failure.",
                  "The commit date (26 Oct 2026) is in the future relative to typical analysis timelines; this is taken at face value from the patch metadata."
                ],
                "capecRationale": [
                  {
                    "capecId": "CAPEC-2",
                    "rationale": "The attacker (a feed host) manipulates the HTTP response status code parameter to a value (203, 206) that the filtering logic does not properly handle, causing the response to bypass all filtering rules. This is the closest CAPEC pattern: the attacker controls an input parameter (the status code) to trigger an unintended code path. Uncertainty: no CAPEC pattern specifically addresses HTTP status code manipulation for proxy bypass; CAPEC-2 is the best available match for parameter-level manipulation to defeat validation logic."
                  }
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                "commit": "b5f606a4e57a49cc4dbf9b3ef0c6ddd19f866735",
                "confidence": "medium",
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                    "value": "Claude Opus 5.5 (1M context)"
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                "cvssRationale": "The vulnerability is exploitable over the network (AV:N) with low complexity (AC:L) since the attacker only needs to return a different HTTP status code. No attack target manipulation (AT:N), no privileges (PR:N) since the attacker is the feed host itself, and no user interaction (UI:N) is required. The vulnerable component (mispguard) itself suffers no direct confidentiality, integrity, or availability impact (VC:N, VI:N, VA:N). The primary impact is on the downstream MISP instance, whose integrity is compromised because unfiltered feed data is ingested (SI:H). No secondary confidentiality or availability impact (SC:N, SA:N) is evidenced.",
                "fixSummary": "The fix adds an explicit check in process_feed_response that rejects any HTTP response with a status code in the 201-299 range (i.e., successful responses other than 200) by returning a 403 Forbidden response. This ensures that only responses with exactly status code 200 are subject to the normal filtering pipeline, and all other 2xx responses are blocked before they can reach the MISP instance, closing the bypass vector.",
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                    "rationale": "The code validated the HTTP status code incompletely: it checked for != 200 to decide whether to pass through, but failed to account for other 2xx codes (201, 203, 206) that represent successful responses whose content MISP may still ingest. The validation logic did not cover the full range of inputs that required filtering, constituting improper input validation."
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