🛡️ CVE-2026-9571 — mattermost-server

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs administrative privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N

• Attack vector: Network — reachable from anywhere that can route to the service.
• Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
• Privileges required: High — administrative rights are needed first.
• User interaction: None — nobody has to be tricked into anything.
• Scope: Unchanged — the damage stays inside the vulnerable component.
• Confidentiality impact: High — total loss, or loss the attacker controls.
• Integrity impact: High — total loss, or loss the attacker controls.
• Availability impact: None.

Weakness class

CVE-2026-9571 is classified as CWE-305: Authentication Bypass by Primary Weakness. The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.

Affected software

CVE-2026-9571 is recorded against 1 package.

• mattermost-server (from 11.7.0 up to 11.7.3)

Timeline and source

Published on 13 July 2026 and last revised on 15 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

mattermost.com

Other advisories for this package

mattermost-server has other advisories on record. If you are patching this one, these are worth checking on the same host:

• CVE-2026-7521 (5.5 Medium, published 28 Jul 2026)
• CVE-2026-10819 (6.5 Medium, published 27 Jul 2026)
• CVE-2026-10600 (4.3 Medium, published 27 Jul 2026)
• CVE-2026-9597 (5.4 Medium, published 13 Jul 2026)
• CVE-2026-9824 (4.3 Medium, published 13 Jul 2026)
• CVE-2026-6850 (6.5 Medium, published 13 Jul 2026)
• CVE-2026-9820 (3.8 Low, published 13 Jul 2026)
• CVE-2026-10106 (6.5 Medium, published 13 Jul 2026)

Same weakness in other software

These advisories are the same class of weakness (CWE-305: Authentication Bypass by Primary Weakness) in other software:

• CVE-2026-35159 (5.3 Medium, published 3 Jul 2026)
• CVE-2026-41052 (9.5 Critical, published 1 Jul 2026)
• CVE-2026-10539 (9.0 Critical, published 1 Jul 2026)
• CVE-2026-6334 (3.1 Low, published 25 Jun 2026)
• CVE-2025-4994 (published 22 Jun 2026)
• CVE-2025-7064 (6.6 Medium, published 11 Jun 2026)
• CVE-2026-25555 (9.8 Critical, published 8 Jun 2026)
• CVE-2026-9798 (4.3 Medium, published 28 May 2026)

Details

Affected Packages

References