Medium severity4.3NVD Advisory· Published May 18, 2026· Updated May 19, 2026
CVE-2026-6340
CVE-2026-6340
Description
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate 7zip archive structure before processing which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted 7zip file with excessive folder declarations.. Mattermost Advisory ID: MMSA-2026-00573
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
github.com/mattermost/mattermost/server/v8Go | >= 11.5.0, < 11.5.2 | 11.5.2 |
github.com/mattermost/mattermost/server/v8Go | >= 10.11.0, < 10.11.14 | 10.11.14 |
github.com/mattermost/mattermost/server/v8Go | >= 11.4.0, < 11.4.4 | 11.4.4 |
github.com/mattermost/mattermost/server/v8Go | < 8.0.0-20260325191733-fb11968f8798 | 8.0.0-20260325191733-fb11968f8798 |
github.com/mattermost/mattermost-serverGo | < 5.3.2-0.20260325191733-fb11968f8798 | 5.3.2-0.20260325191733-fb11968f8798 |
Affected products
2cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*range: >=10.11.0,<10.11.14
- (no CPE)range: 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3
Patches
Vulnerability mechanics
References
4- github.com/advisories/GHSA-cjm8-jxpw-g43mghsaADVISORY
- mattermost.com/security-updatesnvdVendor AdvisoryWEB
- nvd.nist.gov/vuln/detail/CVE-2026-6340ghsaADVISORY
- github.com/mattermost/mattermost/commit/fb11968f8798925c7b75711025bc5f991124ba26ghsaWEB
News mentions
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