GCVE-1-2026-20110 (CVE-2026-88915)
Vulnerability from gna-1 – Published: 2026-09-10 13:03 – Updated: 2026-09-10 13:04
VLAI
EPSS
VEX
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
Severity
CWE
- CWE-862 - Missing Authorization
Assigner
GNA-1
This instance
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/MISP/MISP/commit/3aa3a9a97 | patch |
Impacted products
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"repo": "https://github.com/MISP/MISP",
"vendor": "MISP",
"versions": [
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"lessThanOrEqual": "2.5.45",
"status": "affected",
"version": "0",
"versionType": "semver"
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"credits": [
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"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)"
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"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"
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"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"
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"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
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"attackRequirements": "NONE",
"attackVector": "NETWORK",
"baseScore": 7.1,
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"privilegesRequired": "LOW",
"providerUrgency": "NOT_DEFINED",
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"subConfidentialityImpact": "NONE",
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"valueDensity": "NOT_DEFINED",
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"descriptions": [
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"url": "https://github.com/MISP/MISP/commit/3aa3a9a97"
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"discovery": "UNKNOWN"
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"title": "MISP Event Template Instantiation Bypasses Sharing Group and Tagging Authorization",
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"datePublished": "2026-09-10T13:03:54.652851Z",
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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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.
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.
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