CVE-2025-54499 Insecure string comparison enables timing attacks

What is CVE-2025-54499?

CVE-2025-54499 is a low-severity vulnerability in Mattermost Mattermost Server, published on 16 Oct 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to use constant-time comparison for sensitive string comparisons which allows attackers to exploit timing oracles to perform byte-by-byte brute force attacks via response time analysis on Cloud API keys and OAuth client secrets

Weakness: CWE-208

Which versions are affected by CVE-2025-54499?

10 open source packages ship an affected version, including github.com/mattermost/mattermost-server, github.com/mattermost/mattermost-server/v5 and github.com/mattermost/mattermost-server/v6. It affects 1 product.

Products include Mattermost Mattermost Server.

How do I fix CVE-2025-54499?

Upgrade github.com/mattermost/mattermost-server to a fixed version for your release line: 10.11.3, 10.5.11, 10.5.11+incompatible or 10.11.3+incompatible.

Is CVE-2025-54499 being exploited?

There is no known exploitation of CVE-2025-54499 in the wild and no public exploit code.

Other vulnerabilities in Mattermost Mattermost Server

• CVE-2025-12419 Account takeover on OAuth/OpenID-enabled servers Critical 9.9
• CVE-2025-12421 Account Takeover via Code Exchange Endpoint Critical 9.9
• CVE-2025-4981 Path Traversal Leading to RCE by Any Authenticated Mattermost User Critical 9.9
• CVE-2025-20051 Arbitrary file read via block duplication in Mattermost Boards Critical 9.9
• CVE-2025-25279 Arbitrary file read in Mattermost Boards via import & export board archive Critical 9.9

All Mattermost Mattermost Server vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-xr3w-rmvj-f6m7, GO-2025-4036.