CVE-2026-3495 json
Unescaped variables during error page composition
published 2026-05-18 5 mo ago modified 2026-10-14 25 d ago also GHSA-jx93-pf6x-874r , GO-2026-5484 , EUVD-2026-30742
- cvss
- 3.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 3%
- public exploits
- 0
- none known
Summary
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to escape some variables that could contain malicious content during error page composition which allows an attacker with access to edit some site configuration to execute some malicious code via injecting some JS as part of those values.. Mattermost Advisory ID: MMSA-2026-00622
Patch / fix
- go github.com/mattermost/mattermost/server/v8 8.0.0-20260310115442-5a1ea95044d, 10.11.14, 11.5.2
- go github.com/mattermost/mattermost-server 5.3.2-0.20260310115442-5a1ea95044dc, 10.11.14+incompatible, 11.5.2+incompatible
- Mattermost Mattermost 10.11.14, 11.5.2, 11.6.0
- govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
opensuse advisories openSUSE-SU-2026:21483-1
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 5 mo ago
Exploit prediction
0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 3.8 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N |
| NVD | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N |
| GitHub | 3.1 | 3.8 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| go | github.com/mattermost/mattermost/server/v8 | >=10.11.0, <10.11.14 >=11.5.0, <11.5.2 <8.0.0-20260310115442-5a1ea95044d all versions |
10.11.14 11.5.2 8.0.0-20260310115442-5a1ea95044d |
| go | github.com/mattermost/mattermost-server | <5.3.2-0.20260310115442-5a1ea95044dc >=10.11.0+incompatible, <10.11.14+incompatible >=11.5.0+incompatible, <11.5.2+incompatible |
5.3.2-0.20260310115442-5a1ea95044dc 10.11.14+incompatible 11.5.2+incompatible |
| 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-79 Improper Neutralization of Input During Web Page Generation
References
Sources
- CVE List CVE-2026-3495
- GitHub Advisory GHSA-jx93-pf6x-874r
- NVD CVE-2026-3495
- OSV GO-2026-5484
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.