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Fencer Intel
medium 6.5

CVE-2025-6226 json

IDOR in CreatePost API allows for timeboxed message disclosure

published last yr. modified 4mo ago also GHSA-7h34-9chr-58qh , GO-2025-3819 , EUVD-2025-21867

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

Mattermost versions 10.5.x <= 10.5.6, 10.8.x <= 10.8.1, 10.7.x <= 10.7.3, 9.11.x <= 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of recently created posts.

Patch / fix

  • go github.com/mattermost/mattermost-server 9.11.17, 9.11.17+incompatible, 10.5.7, 10.5.7+incompatible, 10.7.4, 10.7.4+incompatible, 10.8.2, 10.8.2+incompatible
  • go github.com/mattermost/mattermost/server/v8 8.0.0-20250520130510-fa40a8c5d47f
  • Mattermost Mattermost 9.11.17, 10.5.8, 10.7.4, 10.8.2, 10.9.0
  • govulncheck-vulndb openSUSE Tumbleweed 0.0.20250730T213748-1.1

opensuse advisories openSUSE-SU-2025:15405-1

Is CVE-2025-6226 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/mattermost/mattermost-server
>=10.5.0, <10.5.7
>=10.8.0, <10.8.2
>=10.7.0, <10.7.4
>=9.11.0, <9.11.17
>=9.11.0+incompatible, <9.11.17+incompatible
>=10.5.0+incompatible, <10.5.7+incompatible
>=10.7.0+incompatible, <10.7.4+incompatible
>=10.8.0+incompatible, <10.8.2+incompatible
10.5.7
10.8.2
10.7.4
9.11.17
9.11.17+incompatible
10.5.7+incompatible
10.7.4+incompatible
10.8.2+incompatible
go github.com/mattermost/mattermost/server/v8
<8.0.0-20250520130510-fa40a8c5d47f
8.0.0-20250520130510-fa40a8c5d47f
go github.com/mattermost/mattermost-server/v5
all versions
 no fix listed
go github.com/mattermost/mattermost-server/v6
all versions
 no fix listed

Affected products

  • Mattermost Mattermost

Classification

Weakness
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.