WebSphere Application Server - Liberty: Session Fixation
CVE-2026-93909 is a critical-severity session fixation vulnerability in WebSphere Application Server - Liberty from IBM, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected WebSphere Application Server - Liberty versions: 17.0.0.3 through 26.0.0.10. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.38% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Websphere Application Server to 26.0.0.11 or a later version.
- Read the advisory on ibm.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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| IBM | WebSphere Application Server - Liberty | 17.0.0.3 through 26.0.0.10 | Not stated |
| IBM | Websphere Application Server | 17.0.0.3 up to, but not including, 26.0.0.11 | 26.0.0.11 |
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
- NoneNo account or login is needed.
- 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
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (us.ibm.com).
Official description
IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.10 is vulnerable by an authentication bypass vulnerability when samlWeb-2.0 feature is enabled.
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: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in WebSphere Application Server - Liberty
- 7.5 High severity
- 9.1 Critical severity
- 8.2 High severity
- 9.1 Critical severity
- 7.5 High severity
- 8.7 High severity
Recent Session Fixation vulnerabilities
- 8.8 High severity
- 9.1 Critical severity
- 9.8 Critical severity
Zammad GmbH Zammad Session Fixation Exploited
- 7.1 High severity
- 9.8 Critical severity
- 7.4 High severity
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