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Fencer Vulns
medium 4.9

CVE-2025-8402 json

Nil pointer dereference in bulk import crashes server

published 2025-08-21 14 mo ago modified 2026-06-17 4 mo ago also GHSA-h469-4fcf-p23h , GO-2025-3911 , EUVD-2025-25459

cvss
4.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature.

Patch / fix

  • go github.com/mattermost/mattermost-server 9.11.18, 9.11.18+incompatible, 10.5.9, 10.5.9+incompatible, 10.8.4, 10.8.4+incompatible, 10.9.4, 10.9.4+incompatible, 10.10.1, 10.10.1+incompatible
  • go github.com/mattermost/mattermost/server/v8 8.0.0-20250708173752-d6b35c41f0ae5
  • Mattermost Mattermost 9.11.18, 10.5.9, 10.8.4, 10.9.4, 10.10.1, 10.11.0

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
14 mo ago

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 4.9 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
go github.com/mattermost/mattermost-server
>=10.8.0, <10.8.4
>=10.5.0, <10.5.9
>=10.9.0, <10.9.4
>=10.10.0, <10.10.1
>=9.11.0, <9.11.18
>=9.11.0+incompatible, <9.11.18+incompatible
>=10.5.0+incompatible, <10.5.9+incompatible
>=10.8.0+incompatible, <10.8.4+incompatible
>=10.9.0+incompatible, <10.9.4+incompatible
>=10.10.0+incompatible, <10.10.1+incompatible
10.8.4
10.5.9
10.9.4
10.10.1
9.11.18
9.11.18+incompatible
10.5.9+incompatible
10.8.4+incompatible
10.9.4+incompatible
10.10.1+incompatible
go github.com/mattermost/mattermost/server/v8
<8.0.0-20250708173752-d6b35c41f0ae5
all versions
8.0.0-20250708173752-d6b35c41f0ae5
go github.com/mattermost/mattermost-server/v5
<=5.39.3
all versions
 no fix listed
go github.com/mattermost/mattermost-server/v6
<=6.7.2
all versions
 no fix listed

Affected products

  • Mattermost Mattermost

Classification

Weakness
  • CWE-1287 Improper Validation of Specified Type of Input
  • CWE-476 NULL Pointer Dereference

References

Sources

Fencer Vulns 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.