CVE-2026-82840: Apache Wicket session fixation in authentication

CVE-2026-82840 · Severity: info · Published 2026-11-01

Apache Wicket is a Java web framework that handles user authentication through its AuthenticatedWebSession class. Under specific conditions, when a user authenticates a second time (such as for a sensitive action or account switch), the framework fails to renew the session identifier, allowing an attacker who previously planted a session ID in the victim's browser to hijack the authenticated session. This requires the attacker to have special privileges like control of a host on the same domain or access to a servlet container configured to pass session IDs in URLs.

Technologies: Apache Wicket. Vendors: Apache.

Quick answers

Is CVE-2026-82840 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-82840 being exploited in the wild.
How severe is CVE-2026-82840?
Informational severity, published 1 November 2026.
Which products and versions are affected?
Apache Wicket 8.18.0 through 8.19.0, 9.23.0 through 9.24.0, 10.9.0 through 10.11.0.
Is there a fix for CVE-2026-82840?
Yes: fixed in 8.20.0, 9.25.0, 10.12.0. Until then: Renew the session ID from the application's own code on every successful authentication by calling Session#changeSessionId() at the end of the authenticate() method implementation. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-82840 attacked?
It is attacked over the network or from the adjacent network, in a software library.
Am I affected by CVE-2026-82840?
Check whether you run Apache Wicket at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: 8.20.0, 9.25.0, 10.12.0

Renew the session ID from the application's own code on every successful authentication by calling Session#changeSessionId() at the end of the authenticate() method implementation.

Technical details

The session fixation vulnerability exists in AuthenticatedWebSession's signIn() method, which guards session ID renewal (via changeSessionId()) only on the first sign-in transition. Subsequent authentications on an already-signed-in session skip the renewal, though the method still returns true, hiding the failure from callers. The vulnerability requires the attacker to: (1) plant a pre-authenticated session ID in the victim's browser via cross-domain control or URL-based session passing, and (2) trick the victim into re-authenticating on an already-signed-in session. Applications that manually call Session#changeSessionId() after successful authentication are not affected.

Affected products

  • Apache Wicket 8.18.0 through 8.19.0, 9.23.0 through 9.24.0, 10.9.0 through 10.11.0

Timeline

  • 2026-11-01: disclosed

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