What is CVE-2026-4053?

CVE-2026-4053 is a low-severity vulnerability in Mattermost, classified under Operation on a Resource after Expiration or Release. CVSS score: 3.1/10. Published 2026-05-15.

How severe is CVE-2026-4053?

Low severity. CVSS v3 base score is 3.1 out of 10.

Vulnerability in Mattermost

CVE-2026-4053

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

Published 2026-05-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 3.1 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (17.8th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 17.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Mattermost — versions 11.5.0, 10.11.0, 11.6.0
Mattermost Server

Weakness classification (CWE)

CWE-672 — Operation on a Resource after Expiration or Release

References

mattermost.com/security-updates (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-4053?: CVE-2026-4053 is a low-severity vulnerability in Mattermost, classified under Operation on a Resource after Expiration or Release. CVSS score: 3.1/10. Published 2026-05-15.
How severe is CVE-2026-4053?: Low severity. CVSS v3 base score is 3.1 out of 10.