Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to enforce the PostEditTimeLimit on non-message post fields which allows an authenticated user to modify post file attachments, props, and pin status after the edit window has expired via the post patch and update API endpoints.. Mattermost Advisory ID: MMSA-2026-00631
CVE-2026-4053
LOWNVD 3.13.1—
EchelonGraph scoreHIGH confidence
Score 3.1 from GitHub Security Advisory (severity: LOW) published 2026-05-15. NVD baseline CVSS 3.1; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
3.1
- CVSS v3
- 3.1
- EG Score
- 3.1(high)
- EPSS
- 21.6%
- KEV
- Not listed
Published
May 15, 2026
Last Modified
May 18, 2026
References (1)
- responsibledisclosure@mattermosthttps://mattermost.com/security-updates
Frequently asked(5)
What is CVE-2026-4053?
CVE-2026-4053 is a low vulnerability published on May 15, 2026. Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to enforce the PostEditTimeLimit on non-message post fields which allows an authenticated user to modify post file attachments, props, and pin status after the edit window has expired via the post patch and update API endpoints..…
When was CVE-2026-4053 disclosed?
CVE-2026-4053 was first published in the National Vulnerability Database on May 15, 2026, with the most recent update on May 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-4053 actively exploited?
CVE-2026-4053 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 21.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-4053?
CVE-2026-4053 has a CVSS v3 base score of 3.1 (NVD).
How do I remediate CVE-2026-4053?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-4053, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-4053
Is Your Infrastructure Affected by CVE-2026-4053?
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