FKIE_CVE-2026-16044
Vulnerability from fkie_nvd - Published: 2026-08-17 15:16 - Updated: 2026-08-18 20:27
Severity
Summary
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672
References
| URL | Tags | ||
|---|---|---|---|
| responsibledisclosure@mattermost.com | https://mattermost.com/security-updates | Vendor Advisory |
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| mattermost | mattermost_server | * | |
| mattermost | mattermost_server | * |
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Mattermost",
"vendor": "Mattermost",
"versions": [
{
"lessThanOrEqual": "11.7.6",
"status": "affected",
"version": "11.7.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "10.11.21",
"status": "affected",
"version": "10.11.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "11.9.0"
},
{
"status": "unaffected",
"version": "11.7.7"
},
{
"status": "unaffected",
"version": "10.11.22"
}
]
}
],
"source": "responsibledisclosure@mattermost.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"matchCriteriaId": "B064B1E6-B324-4701-8A07-A0B0028C73BB",
"versionEndExcluding": "10.11.22",
"versionStartIncluding": "10.11.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"matchCriteriaId": "DA4EEA22-A3E7-43AF-91F7-4B597F944100",
"versionEndExcluding": "11.7.7",
"versionStartIncluding": "11.7.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Mattermost versions 11.7.x \u003c= 11.7.6, 10.11.x \u003c= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672"
}
],
"id": "CVE-2026-16044",
"lastModified": "2026-08-18T20:27:55.643",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "LOW",
"baseScore": 5.4,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "LOW",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 2.5,
"source": "responsibledisclosure@mattermost.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-16044",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-17T14:50:45.509454Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-08-17T15:16:53.857",
"references": [
{
"source": "responsibledisclosure@mattermost.com",
"tags": [
"Vendor Advisory"
],
"url": "https://mattermost.com/security-updates"
}
],
"sourceIdentifier": "responsibledisclosure@mattermost.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-863"
}
],
"source": "responsibledisclosure@mattermost.com",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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