PT-2026-25702 · Mattermost · Mattermost

Winfunc · CVE-2026-25783 · Published 2026-02-13 · Updated 2026-07-30

Positive Technologies (AI Summary)

CVSS v3.1

4.3

Medium

Base vector

AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.10 Mattermost versions 11.2.x through 11.2.2 Mattermost versions 11.3.x through 11.3.0

Description The software does not properly validate User-Agent header tokens. This allows an authenticated attacker to cause a request panic by using a specially crafted User-Agent header. The User-Agent header is the target of this issue.

Recommendations Update Mattermost to a version later than 10.11.10. Update Mattermost to a version later than 11.2.2. Update Mattermost to a version later than 11.3.0.

Exploit

Fix

DoS

Weakness Enumeration

CWE-1287

Related Identifiers

BDU:2026-06574

CVE-2026-25783

GHSA-2V3W-6G35-5F9V

GO-2026-4725

OPENSUSE-SU-2026:21483-1

SUSE-SU-2026:1135-1

Affected Products

Mattermost

References · 1749

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25783.json · Exploit
• https://osv.dev/vulnerability/GO-2026-4725 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-25783 · Vendor Advisory
• https://mattermost.com/security-updates · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-06574 · Security Note
• https://osv.dev/vulnerability/SUSE-SU-2026:1135-1 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-2v3w-6g35-5f9v · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-25783 · Security Note
• https://osv.dev/vulnerability/openSUSE-SU-2026:21483-1 · Vendor Advisory
• https://github.com/mattermost/mattermost · Note
• https://github.com/mattermost/mattermost/commit/1346cf529aef0672c39a56ec10d1b8a9c8fb387d · Note
• https://github.com/advisories/GHSA-2v3w-6g35-5f9v · Note
• https://suse.com/security/cve/CVE-2025-65797 · Note
• https://suse.com/security/cve/CVE-2026-44427 · Note
• https://suse.com/security/cve/CVE-2026-7736 · Note