{
"id": "GHSA-j76w-p754-g2w7",
"aliases": [
"CVE-2026-4054"
],
"details": "Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate the response body of proxied images, which allows a remote attacker to enact client-side DoS via an SVG file served from an attacker-controlled origin under a non-SVG Content-Type header (e.g. image/png) embedded in an og:image meta tag or Markdown image link. Mattermost Advisory ID: MMSA-2026-00630.",
"summary": "Mattermost doesn't validate the response body of proxied images",
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "11.5.0"
},
{
"fixed": "11.5.2"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost-server",
"ecosystem": "Go"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0.0.0-20250731163400-5b955468ea1e"
},
{
"fixed": "0.0.0-20260414103857-b21ef302025e"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost-server",
"ecosystem": "Go"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "11.4.0"
},
{
"fixed": "11.4.4"
}
]
}
],
"package": {
"name": "github.com/mattermost/mattermost-server",
"ecosystem": "Go"
}
}
],
"modified": "2026-05-28T19:28:48Z",
"severity": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L"
}
],
"published": "2026-05-15T21:31:33Z",
"references": [
{
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-4054",
"type": "ADVISORY"
},
{
"url": "https://github.com/mattermost/mattermost",
"type": "PACKAGE"
},
{
"url": "https://mattermost.com/security-updates",
"type": "WEB"
}
],
"schema_version": "1.4.0",
"database_specific": {
"cwe_ids": [
"CWE-754"
],
"severity": "MODERATE",
"github_reviewed": true,
"nvd_published_at": "2026-05-15T19:17:04Z",
"github_reviewed_at": "2026-05-28T19:28:48Z"
}
}