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Mattermost doesn't enforce the PostEditTimeLimit on non-message post fields

Low severity GitHub Reviewed Published May 15, 2026 to the GitHub Advisory Database • Updated May 28, 2026

Package

gomod github.com/mattermost/mattermost-server (Go)

Affected versions

>= 11.5.0, < 11.5.2
>= 0.0.0-20250731163400-5b955468ea1e, < 0.0.0-20260414103857-b21ef302025e

Patched versions

11.5.2
0.0.0-20260414103857-b21ef302025e

Description

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.

References

Published by the National Vulnerability Database May 15, 2026
Published to the GitHub Advisory Database May 15, 2026
Reviewed May 28, 2026
Last updated May 28, 2026

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(22nd percentile)

Weaknesses

Operation on a Resource after Expiration or Release

The product uses, accesses, or otherwise operates on a resource after that resource has been expired, released, or revoked. Learn more on MITRE.

CVE ID

CVE-2026-4053

GHSA ID

GHSA-hw87-6jcq-9f8q

Source code

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