CVE-2026-3114: Mattermost doesn't validate decompressed archive entry sizes during file extraction

March 26, 2026 (updated March 31, 2026)

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to validate decompressed archive entry sizes during file extraction which allows authenticated users with file upload permissions to cause a denial of service via crafted zip archives containing highly compressed entries (zip bombs) that exhaust server memory. Mattermost Advisory ID: MMSA-2026-00598.

References

github.com/advisories/GHSA-vhgh-g7x8-4rx8
github.com/mattermost/mattermost
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2026-3114

Code Behaviors & Features

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