Mattermost has missing redirect URL validation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2025-62690: 0.15% estimated exploitation activity in the next 30 days; percentile 4.09 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Mattermost versions 10.11.x <= 10.11.4 fail to validate redirect URLs on the /error page, which allows an attacker to redirect a victim to a malicious site via a crafted link opened in a new tab.

Published by the source

17 Dec 2025, 15:34 UTC

Last modified by the source

18 Dec 2025, 15:25 UTC

Source last checked

26 Oct 2026, 15:13 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-q66g-q98c-q454

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# Patch Next advisory brief: CVE-2025-62690

Advisory: Mattermost has missing redirect URL validation
IDs: CVE-2025-62690, GHSA-q66g-q98c-q454
Record: https://patchnext.com/advisories/cve-2025-62690 (revision 1, source checked 26 Oct 2026, 15:13 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/mattermost/mattermost/server/v8 8.0.0-20251016131338-dad6bd7a1509; github.com/mattermost/mattermost 11.1.0, 10.11.5-0.20251016131338-dad6bd7a1509. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mattermost/mattermost/server/v8: affected >= 8.0.0-20250721062209-4952acea88ce, < 8.0.0-20251016131338-dad6bd7a1509; fixed in 8.0.0-20251016131338-dad6bd7a1509
- Go github.com/mattermost/mattermost: affected >= 10.11.0-rc1, < 10.11.5-0.20251016131338-dad6bd7a1509; >= 11.0.0-alpha.1, < 11.1.0; fixed in 11.1.0, 10.11.5-0.20251016131338-dad6bd7a1509

## Suggested inspection (read-only)
- Go github.com/mattermost/mattermost/server/v8: check the installed version with your package manager.
- Go github.com/mattermost/mattermost: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-q66g-q98c-q454 (GitHub-reviewed advisory GHSA-q66g-q98c-q454 lists affected ranges: Go github.com/mattermost/mattermost/server/v8 >=8.0.0-20250721062209-4952acea88ce =10.11.0-rc1 =11.0.0-alpha.1 <11.1.0)

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