Low
Markdown image rendering bypass in AI bot tool result posts in Mattermost
Type: advisorySources: OSV
Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows an authenticated attacker to exfiltrate data to an attacker-controlled server via injecting markdown image syntax into tool result content rendered by a victim's client.. Mattermost Advisory ID: MMSA-2026-00619
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-3472
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 7 Nov 2026, 13:12 UTC · Revision 1
Source evidence
Markdown image rendering bypass in AI bot tool result posts in Mattermost
core-osv · Original sourcePublished 26 Jun 2026, 14:42 UTC
Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows an authenticated attacker to exfiltrate data to an attacker-controlled server via injecting markdown image syntax into tool result content rendered by a victim's client.. Mattermost Advisory ID: MMSA-2026-00619
osv:CVE-2026-3472
Complete source record
{
"id": "e1a972193443b37c9a17dae6187e390d1ae7f78d55dcc1a3956edbde78fb5729",
"url": "https://osv.dev/vulnerability/CVE-2026-3472",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Markdown image rendering bypass in AI bot tool result posts in Mattermost",
"summary": "Mattermost versions 10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x <= 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows an authenticated attacker to exfiltrate data to an attacker-controlled server via injecting markdown image syntax into tool result content rendered by a victim's client.. Mattermost Advisory ID: MMSA-2026-00619",
"evidence": "osv:CVE-2026-3472",
"products": [],
"severity": "low",
"structured": {
"id": "CVE-2026-3472",
"aliases": [
"CVE-2026-3472"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/mattermost/mattermost",
"type": "GIT",
"events": [
{
"introduced": "5b955468ea1ea8b56c0fb10feb258a36a767d7bb"
},
{
"fixed": "4439c6121d009e1b7a16bad504e62627572cf157"
},
{
"introduced": "9f2616376582893035a7e3cb38b0fab648bba4e8"
},
{
"fixed": "7395f2ba2f17aa328fde4856101bb927aa80dc1f"
},
{
"introduced": "d4f4e78835e86e2e76f76bfe797623076f5c9835"
},
{
"fixed": "374d6843170180aea130e92a4925b26cbdafca5d"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "10.11.0"
},
{
"fixed": "10.11.19"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "11.5.0"
},
{
"fixed": "11.5.7"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "11.6.0"
},
{
"fixed": "11.6.4"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v10.11.19-rc1",
"v11.6.3",
"v10.11.18",
"v11.5.6",
"v11.6.2",
"v11.5.5",
"v10.11.17",
"v10.11.16",
"v10.11.15-rc1",
"v10.11.15",
"v11.5.4",
"v11.6.1-rc1",
"v11.6.1",
"v11.5.3",
"v10.11.14",
"v11.5.2-rc3",
"v11.5.2",
"v11.6.0",
"v10.11.14-rc1",
"v11.5.0",
"v11.5.2-rc2",
"v11.5.2-rc1",
"v10.11.13",
"v11.5.1",
"v10.11.13-rc1",
"v10.11.12",
"v10.11.11-rc2",
"v10.11.11",
"v10.11.11-rc1",
"v10.11.10",
"v10.11.9",
"v10.11.9-rc1",
"v10.11.8",
"v10.11.7",
"v10.11.6",
"v10.11.5",
"v10.11.4-rc3",
"v10.11.4",
"v10.11.4-rc2",
"v10.11.4-rc1",
"v10.11.3",
"v10.11.2-rc2",
"v10.11.2",
"v10.11.2-rc1",
"v10.11.1",
"v10.11.1-rc1",
"v10.11.0-rc3",
"v10.11.0",
"mattermost-redux@10.11.0",
"@mattermost/types@10.11.0",
"@mattermost/client@10.11.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-3472.json"
}
}
],
"modified": "2026-10-28T02:30:50.620030191Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3472.json",
"https://mattermost.com/security-updates",
"https://nvd.nist.gov/vuln/detail/CVE-2026-3472"
],
"provider_metadata": {
"cwe_ids": [
"CWE-693"
],
"cna_assigner": "Mattermost",
"unresolved_ranges": [
{
"extracted_events": [
{
"range": [
{
"introduced": "10.11.0"
},
{
"last_affected": "10.11.18"
},
{
"introduced": "11.6.0"
},
{
"last_affected": "11.6.3"
},
{
"introduced": "11.5.0"
},
{
"last_affected": "11.5.6"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
}
]
}
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3472.json"
}
},
"related_cves": [
{
"value": "CVE-2026-3472",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 519409,
"published_at": "2026-06-26T14:42:24.154+00:00"
}