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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-6673

26
FAUCET Score

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

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

Impacted Technologies

VendorProductVersion(s)CPE
>= 10.11.0, < 10.11.18CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.5.0, < 11.5.6CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.6.0, < 11.6.3CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 11.7.0, < 11.7.1CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
>= 10.11.0, <= 10.11.17CPE match
cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.4MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.2
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.30%
Probability of exploitation in next 30 days
EPSS Percentile
22.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0030 is in the 45th percentile among its peer group of 144 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 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

mattermost.com / security-updates
Vendor Advisory