Vulnerability-Lookup

CVE-2026-57209 (GCVE-0-2026-57209)

Vulnerability from cvelistv5 – Published: 2026-10-23 12:27 – Updated: 2026-10-23 12:27

Title

Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode

Summary

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.17, when Heimdall operates in proxy mode, it constructs the Forwarded HTTP header after executing the matched rule pipeline by inserting the incoming request's Host header value directly into the header string without sanitizing commas or semicolons. This allows an attacker to inject additional parameters into the Forwarded header, potentially spoofing IP addresses for upstream services. This issue has been patched in version 0.17.17.

Severity

7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

CWE

CWE-20 - Improper Input Validation
CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7761 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/dadrus/heimdall/security/advis…	x_refsource_CONFIRM
https://github.com/dadrus/heimdall/releases/tag/v…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
dadrus	heimdall	Affected: < 0.17.17	guessed

Show details on NVD website

JSON

To clipboard

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        }
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            }
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        "shortName": "GitHub_M"
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      "source": {
        "advisory": "GHSA-4jgr-pg2m-m988",
        "discovery": "UNKNOWN"
      },
      "title": "Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-57209",
    "datePublished": "2026-10-23T12:27:19.621Z",
    "dateReserved": "2026-06-24T02:00:46.801Z",
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                "vendor": "dadrus",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 0.17.17"
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          }
        ],
        "id": "CVE-2026-57209",
        "lastModified": "2026-10-23T19:57:42.660",
        "metrics": {
          "cvssMetricV40": [
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              "cvssData": {
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                "Recovery": "NOT_DEFINED",
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                "attackComplexity": "LOW",
                "attackRequirements": "PRESENT",
                "attackVector": "NETWORK",
                "availabilityRequirement": "NOT_DEFINED",
                "baseScore": 7.0,
                "baseSeverity": "HIGH",
                "confidentialityRequirement": "NOT_DEFINED",
                "exploitMaturity": "NOT_DEFINED",
                "integrityRequirement": "NOT_DEFINED",
                "modifiedAttackComplexity": "NOT_DEFINED",
                "modifiedAttackRequirements": "NOT_DEFINED",
                "modifiedAttackVector": "NOT_DEFINED",
                "modifiedPrivilegesRequired": "NOT_DEFINED",
                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
                "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "HIGH",
                "subIntegrityImpact": "HIGH",
                "userInteraction": "NONE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
                "version": "4.0",
                "vulnAvailabilityImpact": "NONE",
                "vulnConfidentialityImpact": "NONE",
                "vulnIntegrityImpact": "NONE",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-10-23T13:17:11.687",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/dadrus/heimdall/releases/tag/v0.17.17"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/dadrus/heimdall/security/advisories/GHSA-4jgr-pg2m-m988"
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        "vulnStatus": "Deferred",
        "weaknesses": [
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    }
  }
}

FKIE_CVE-2026-57209

Vulnerability from fkie_nvd - Published: 2026-10-23 13:17 - Updated: 2026-10-23 19:57

Severity

7.0 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/dadrus/heimdall/releases/tag/v0.17.17
	security-advisories@github.com	https://github.com/dadrus/heimdall/security/advisories/GHSA-4jgr-pg2m-m988

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "heimdall",
          "vendor": "dadrus",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.17.17"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.17, when Heimdall operates in proxy mode, it constructs the Forwarded HTTP header after executing the matched rule pipeline by inserting the incoming request\u0027s Host header value directly into the header string without sanitizing commas or semicolons. This allows an attacker to inject additional parameters into the Forwarded header, potentially spoofing IP addresses for upstream services. This issue has been patched in version 0.17.17."
    }
  ],
  "id": "CVE-2026-57209",
  "lastModified": "2026-10-23T19:57:42.660",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 7.0,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "HIGH",
          "subIntegrityImpact": "HIGH",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
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  "published": "2026-10-23T13:17:11.687",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/dadrus/heimdall/releases/tag/v0.17.17"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/dadrus/heimdall/security/advisories/GHSA-4jgr-pg2m-m988"
    }
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        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

GHSA-4JGR-PG2M-M988

Vulnerability from github – Published: 2026-06-18 14:24 – Updated: 2026-07-20 21:28

Summary

Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode

Details

Summary

When Heimdall operates in proxy mode, it constructs the Forwarded HTTP header after executing the matched rule pipeline by inserting the incoming request's Host header value directly into the header string without sanitizing commas or semicolons. This allows an attacker to inject additional parameters into the Forwarded header, potentially spoofing IP addresses for upstream services.

Vulnerable Code

File: proxy/request_context.go (line 201)

entry := "for=" + clientIP + ";host=" + in.Host + ";proto=" + proto

Go's net/http allows commas and semicolons in Host header values. No sanitization is applied before string concatenation.

PoC

# Inject a spoofed IP into the Forwarded header
curl -s -H "Host: evil.com,for=127.0.0.1" \
  "http://TARGET:PORT/protected-resource"

This produces the following Forwarded header sent to the upstream service:

Forwarded: for=1.2.3.4;host=evil.com, for=127.0.0.1;proto=http

Upstream services that parse the Forwarded header according to RFC 7239 will see two entries. If the service trusts the last or any for= value, the attacker successfully spoofs 127.0.0.1 as the client IP.

# More targeted attack: spoof to bypass IP allowlist
curl -s -H "Host: legit.com;for=10.0.0.1;proto=https,for=192.168.1.1" \
  "http://TARGET:PORT/admin-panel"

Impact

IP spoofing: Upstream services behind Heimdall may trust the injected for= value, believing the request originates from an internal/trusted IP
Access control bypass: Applications that restrict access based on IP address by themselves, without using the corresponding heimdall capabilities (e.g., admin panels, internal APIs), can be bypassed
Affects all proxy-mode deployments where upstream services parse the Forwarded header.

Severity

7.0 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.17.16"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/dadrus/heimdall"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.17.17"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-57209"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-74"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-18T14:24:41Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\nWhen Heimdall operates in proxy mode, it constructs the `Forwarded` HTTP header after executing the matched rule pipeline by inserting the incoming request\u0027s `Host` header value directly into the header string without sanitizing commas or semicolons. This allows an attacker to inject additional parameters into the `Forwarded` header, potentially spoofing IP addresses for upstream services.\n\n### Vulnerable Code\n\n**File: `proxy/request_context.go` (line 201)**\n\n```go\nentry := \"for=\" + clientIP + \";host=\" + in.Host + \";proto=\" + proto\n```\n\nGo\u0027s `net/http` allows commas and semicolons in Host header values. No sanitization is applied before string concatenation.\n\n### PoC\n\n```bash\n# Inject a spoofed IP into the Forwarded header\ncurl -s -H \"Host: evil.com,for=127.0.0.1\" \\\n  \"http://TARGET:PORT/protected-resource\"\n```\n\nThis produces the following `Forwarded` header sent to the upstream service:\n\n```\nForwarded: for=1.2.3.4;host=evil.com, for=127.0.0.1;proto=http\n```\n\nUpstream services that parse the `Forwarded` header according to RFC 7239 will see two entries. If the service trusts the last or any `for=` value, the attacker successfully spoofs `127.0.0.1` as the client IP.\n\n```bash\n# More targeted attack: spoof to bypass IP allowlist\ncurl -s -H \"Host: legit.com;for=10.0.0.1;proto=https,for=192.168.1.1\" \\\n  \"http://TARGET:PORT/admin-panel\"\n```\n\n### Impact\n\n- **IP spoofing:** Upstream services behind Heimdall may trust the injected `for=` value, believing the request originates from an internal/trusted IP\n- **Access control bypass:** Applications that restrict access based on IP address by themselves, without using the corresponding heimdall capabilities (e.g., admin panels, internal APIs), can be bypassed\n- **Affects all proxy-mode deployments** where upstream services parse the `Forwarded` header.",
  "id": "GHSA-4jgr-pg2m-m988",
  "modified": "2026-07-20T21:28:46Z",
  "published": "2026-06-18T14:24:41Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/dadrus/heimdall/security/advisories/GHSA-4jgr-pg2m-m988"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/dadrus/heimdall"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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CVE-2026-57209 (GCVE-0-2026-57209)

FKIE_CVE-2026-57209

GHSA-4JGR-PG2M-M988

Summary

Vulnerable Code

PoC

Impact

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour