Bug 2527618 (CVE-2026-84652)

Summary: CVE-2026-84652 jenkins: Jenkins: Authentication bypass via session cookie non-rotation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Jenkins. When a user authenticates using the "remember me" cookie, Jenkins fails to rotate the session identifier. This oversight allows a remote attacker, who can serve content on the same site as Jenkins, to set a known session cookie in a victim's browser. Consequently, once the victim authenticates, the attacker can use the known session cookie to gain unauthorized access to Jenkins as that user, leading to an authentication bypass.
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Description OSIDB Bzimport 2026-09-02 16:04:31 UTC 
In Jenkins 2.579 and earlier, LTS 2.568.2 and earlier, Jenkins does not rotate the session when a user is authenticated via the "remember me" cookie, allowing attackers able to serve content on the same site as Jenkins to set a known session cookie in the victim's browser, which after the victim authenticates via the "remember me" cookie, grants the attacker access to Jenkins as that user.