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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-4646

22
FAUCET Score

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate user-supplied input in API request handlers which allows an authenticated attacker to crash the plugin process via a crafted HTTP request to the PR details endpoint.. Mattermost Advisory ID: MMSA-2026-00638

First published: May 22, 2026Last modified: May 22, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 10.11.0, < 10.11.15CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.4.0, < 11.4.5CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.5.0, < 11.5.4CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.6.0, < 11.6.1CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 10.11.0, <= 10.11.14CPE match
cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.3MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.25%
Probability of exploitation in next 30 days
EPSS Percentile
16.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0025 is in the 20th percentile among its peer group of 21,977 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 11.6.1
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 11.5.4
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 11.4.5
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-serverFixed in: 10.11.15
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-plugin-githubFixed in: 1.0.1-0.20260330164815-c2840e980b3c

Vendor Advisories (1)

goGHSA-rmvv-8v8w-rf7xmedium

Mattermost doesn't validate user-supplied input in API request handlers

May 26, 2026

References

mattermost.com / security-updates
Vendor Advisory