authentik: Session Fixation
CVE-2025-29928 is a high-severity session fixation vulnerability in authentik from Goauthentik, with a CVSS 3.1 base score of 8.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected authentik versions: < 2024.12.4; < 2025.2.3. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.39% 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
- Check which version of authentik you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Goauthentik | authentik | < 2024.12.4; < 2025.2.3 | Not stated |
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
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N. Scored by CNA (github.com).
Official description
authentik is an open-source identity provider. Prior to versions 2024.12.4 and 2025.2.3, when authentik was configured to use the database for session storage (which is a non-default setting), deleting sessions via the Web Interface or the API would not revoke the session and the session holder would continue to have access to authentik. authentik 2025.2.3 and 2024.12.4 fix this issue. Switching to the cache-based session storage until the authentik instance can be upgraded is recommended. This will however also delete all existing sessions and users will have to re-authenticate.
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: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in authentik
- 7.5 High severity
- 7.4 High severity
- 8.1 High severity
- 8.8 High severity
- 8.9 High severity
- 8.8 High severity
Recent Session Fixation vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 10.0 Critical severity
- 9.1 Critical severity
- 8.8 High severity
- 9.1 Critical severity
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