Mattermost: Session Fixation
CVE-2025-1412 is a high-severity session fixation vulnerability in Mattermost, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected Mattermost versions: 9.11.0 through 9.11.6; 10.4.0 through 10.4.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.26% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Mattermost Server to 9.11.7 or 10.4.2, whichever matches your release line, or a later version.
- Read the advisory on mattermost.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Mattermost | Mattermost | 9.11.0 through 9.11.6; 10.4.0 through 10.4.1 | Not stated |
| Mattermost | Mattermost Server | 9.11.0 up to, but not including, 9.11.7; 10.4.0 up to, but not including, 10.4.2 | 9.11.7, 10.4.2 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 3.1 | Low | CNA (mattermost.com) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
Mattermost versions 9.11.x <= 9.11.6, 10.4.x <= 10.4.1 fail to invalidate all active sessions when converting a user to a bot, with allows the converted user to escalate their privileges depending on the permissions granted to the bot.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Session Fixation
Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.
How developers prevent this class of flaw
- Invalidate any existing session identifiers prior to authorizing a new user session.
- For platforms such as ASP that do not generate new values for sessionid cookies, utilize a secondary cookie. In this approach, set a secondary cookie on the user's browser to a random value and set a session variable to the same value. If the session variable and the cookie value ever don't match, invalidate the session, and force the user to log on again.
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in Mattermost
- 8.0 High severity
- 7.1 High severity
- 9.3 Critical severity
- 7.1 High severity
Recent Session Fixation vulnerabilities
- 9.8 Critical severity
- 10.0 Critical severity
- 9.1 Critical severity
- 8.8 High severity
- 9.1 Critical severity
- 8.8 High severity
Spotted an error? Tell us.