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GCVE-1-2026-20110 (CVE-2026-88915)

Vulnerability from gna-1 – Published: 2026-09-10 13:03 – Updated: 2026-09-10 13:04
VLAI
Title
MISP Event Template Instantiation Bypasses Sharing Group and Tagging Authorization
Summary
Affected versions of MISP do not consistently enforce the acting user's authorization when instantiating event templates. For templates using distribution = 4, the template can specify a sharing_group_id. The instantiation path passed that value into event creation without verifying that the user instantiating the template was actually permitted to use the selected sharing group. The commit notes that Event::_add() only performed its own sharing-group authorization in another code path, leaving template instantiation able to write the identifier directly. The same instantiation path also attached template-specified tags without checking the user's normal tagging permissions. In addition, it hardcoded local => 0, meaning tags marked local_only could be attached globally and consequently propagate through synchronization or export, contrary to their intended restriction. The fix adds explicit SharingGroup::canUse() authorization for the acting user, applies the same tag-modification checks used by normal event tagging, and ensures local_only tags are attached locally. Version affected: ≤2.5.45
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
MISP MISP Affected: 0 , ≤ 2.5.45 (semver)
guessed Create a notification for this product.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "MISP",
          "repo": "https://github.com/MISP/MISP",
          "vendor": "MISP",
          "versions": [
            {
              "lessThanOrEqual": "2.5.45",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Scottish Government - National Cyber Team"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "iglocska"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Claude Opus 5 (1M context)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
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              "type": "text/html",
              "value": "\u003cp\u003eAffected versions of MISP do not consistently enforce the acting user\u0027s authorization when instantiating event templates.\u003c/p\u003e\n\u003cp\u003eFor templates using \u003ccode\u003edistribution = 4\u003c/code\u003e, the template can specify a \u003ccode\u003esharing_group_id\u003c/code\u003e. The instantiation path passed that value into event creation without verifying that the user instantiating the template was actually permitted to use the selected sharing group. The commit notes that \u003ccode\u003eEvent::_add()\u003c/code\u003e only performed its own sharing-group authorization in another code path, leaving template instantiation able to write the identifier directly.\u003c/p\u003e\n\u003cp\u003eThe same instantiation path also attached template-specified tags without checking the user\u0027s normal tagging permissions. In addition, it hardcoded \u003ccode\u003elocal =\u0026gt; 0\u003c/code\u003e, meaning tags marked \u003ccode\u003elocal_only\u003c/code\u003e could be attached globally and consequently propagate through synchronization or export, contrary to their intended restriction.\u003c/p\u003e\n\u003cp\u003eThe fix adds explicit \u003ccode\u003eSharingGroup::canUse()\u003c/code\u003e authorization for the acting user, applies the same tag-modification checks used by normal event tagging, and ensures \u003ccode\u003elocal_only\u003c/code\u003e tags are attached locally.\u003c/p\u003eVersion affected: \u22642.5.45\u003cbr\u003e"
            }
          ],
          "value": "Affected versions of MISP do not consistently enforce the acting user\u0027s authorization when instantiating event templates.\n\n\nFor templates using distribution = 4, the template can specify a sharing_group_id. The instantiation path passed that value into event creation without verifying that the user instantiating the template was actually permitted to use the selected sharing group. The commit notes that Event::_add() only performed its own sharing-group authorization in another code path, leaving template instantiation able to write the identifier directly.\n\n\nThe same instantiation path also attached template-specified tags without checking the user\u0027s normal tagging permissions. In addition, it hardcoded local =\u003e 0, meaning tags marked local_only could be attached globally and consequently propagate through synchronization or export, contrary to their intended restriction.\n\n\nThe fix adds explicit SharingGroup::canUse() authorization for the acting user, applies the same tag-modification checks used by normal event tagging, and ensures local_only tags are attached locally.\n\nVersion affected: \u22642.5.45"
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-1",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-1 Accessing Functionality Not Properly Constrained by ACLs"
            }
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        }
      ],
      "metrics": [
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          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
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      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-862",
              "description": "CWE-862 Missing Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "orgId": "00000000-0000-4000-9000-000000000000"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/MISP/MISP/commit/3aa3a9a97"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "MISP Event Template Instantiation Bypasses Sharing Group and Tagging Authorization",
      "x_gcve": [
        {
          "recordType": "advisory",
          "vulnId": "gcve-1-2026-20110"
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      ],
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
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  "cveMetadata": {
    "assignerOrgId": "00000000-0000-4000-9000-000000000000",
    "cveId": "CVE-2026-88915",
    "datePublished": "2026-09-10T13:03:54.652851Z",
    "dateReserved": "2026-09-10T13:04:01.032Z",
    "dateUpdated": "2026-09-10T13:04:01.471196Z",
    "requesterUserId": "00000000-0000-4000-9000-000000000000",
    "serial": 1,
    "state": "PUBLISHED",
    "vulnId": "GCVE-1-2026-20110"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}



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