CVE-2026-4055 (GCVE-0-2026-4055)
Vulnerability from cvelistv5 – Published: 2026-05-21 07:13 – Updated: 2026-05-21 07:13
VLAI?
Title
Insufficient permission validation on cross-team playbook run creation
Summary
Mattermost versions 11.5.x <= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629
Severity ?
4.3 (Medium)
CWE
- CWE-863 - Incorrect Authorization
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.5.0 , ≤ 11.5.1
(semver)
Unaffected: 11.6.0 Unaffected: 11.5.2 Unaffected: 10.11.14 Unaffected: 11.4.4 |
Credits
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Mattermost",
"vendor": "Mattermost",
"versions": [
{
"lessThanOrEqual": "11.5.1",
"status": "affected",
"version": "11.5.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "11.6.0"
},
{
"status": "unaffected",
"version": "11.5.2"
},
{
"status": "unaffected",
"version": "10.11.14"
},
{
"status": "unaffected",
"version": "11.4.4"
}
]
}
],
"credits": [
{
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"type": "finder",
"value": "0x7oda7123"
}
],
"descriptions": [
{
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"value": "Mattermost versions 11.5.x \u003c= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629"
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 4.3,
"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:N",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-863",
"description": "CWE-863: Incorrect Authorization",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-21T07:13:31.669Z",
"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
"shortName": "Mattermost"
},
"references": [
{
"name": "MMSA-2026-00629",
"tags": [
"vendor-advisory"
],
"url": "https://mattermost.com/security-updates"
}
],
"solutions": [
{
"lang": "en",
"value": "Update Mattermost to versions 11.6.0, 11.5.2, 10.11.14, 11.4.4 or higher."
}
],
"source": {
"advisory": "MMSA-2026-00629",
"defect": [
"https://mattermost.atlassian.net/browse/MM-67858"
],
"discovery": "EXTERNAL"
},
"title": "Insufficient permission validation on cross-team playbook run creation",
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
"assignerShortName": "Mattermost",
"cveId": "CVE-2026-4055",
"datePublished": "2026-05-21T07:13:31.669Z",
"dateReserved": "2026-03-12T16:09:11.995Z",
"dateUpdated": "2026-05-21T07:13:31.669Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-4055\",\"sourceIdentifier\":\"responsibledisclosure@mattermost.com\",\"published\":\"2026-05-21T08:16:23.130\",\"lastModified\":\"2026-05-21T08:16:23.130\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Mattermost versions 11.5.x \u003c= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"responsibledisclosure@mattermost.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N\",\"baseScore\":4.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.8,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"responsibledisclosure@mattermost.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-863\"}]}],\"references\":[{\"url\":\"https://mattermost.com/security-updates\",\"source\":\"responsibledisclosure@mattermost.com\"}]}}"
}
}
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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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