🛡️ CVE-2026-3637 — mattermost-server

How this vulnerability can be exploited

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

CVSS metrics in full

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

• Attack vector: Network — reachable from anywhere that can route to the service.
• Attack complexity: Low — the attack works reliably, with no preparation.
• Privileges required: Low — an ordinary user account is enough.
• User interaction: None — nobody has to be tricked into anything.
• Scope: Unchanged — the damage stays inside the vulnerable component.
• Confidentiality impact: None.
• Integrity impact: Low — limited, and the attacker does not choose what is affected.
• Availability impact: None.

Weakness class

CVE-2026-3637 is classified as CWE-862: Missing Authorization. No authorisation check is performed before carrying out a restricted action.

Affected software

CVE-2026-3637 is recorded against 5 packages.

• github.com/mattermost/mattermost-server
• github.com/mattermost/mattermost-server/v5
• github.com/mattermost/mattermost-server/v6
• github.com/mattermost/mattermost/server/v8
• mattermost-server (from 11.5.0 up to 11.5.2)

Timeline and source

Published on 18 May 2026 and last revised on 25 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

nvd.nist.gov (Advisory)
github.com (Web)
github.com (Package)
mattermost.com (Web)

Other advisories for this package

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

• CVE-2026-4646 (published 7 Jul 2026)
• CVE-2026-5755 (published 7 Jul 2026)
• CVE-2026-28735 (published 7 Jul 2026)
• CVE-2026-4635 (published 7 Jul 2026)
• CVE-2026-5308 (8.0 High, published 7 Jul 2026)
• CVE-2026-3473 (8.0 High, published 7 Jul 2026)
• CVE-2026-3115 (published 25 Jun 2026)
• CVE-2026-4054 (published 25 Jun 2026)

Same weakness in other software

These advisories are the same class of weakness (CWE-862: Missing Authorization) in other software:

• CVE-2014-0167 (published 6 Jul 2026)
• CVE-2022-0932 (6.5 Medium, published 2 Jul 2026)
• CVE-2024-23752 (9.5 Critical, published 29 Jun 2026)
• CVE-2024-24709 (4.3 Medium, published 17 Jun 2026)
• CVE-2023-32959 (4.3 Medium, published 11 Jun 2026)
• CVE-2023-25969 (5.4 Medium, published 11 Jun 2026)
• CVE-2022-42479 (5.4 Medium, published 11 Jun 2026)
• CVE-2022-45813 (5.4 Medium, published 11 Jun 2026)

Details

Affected Packages

References