Jenkins Stapler CSRF Token Leak 2.447-2.579 via SameSite JS
CVE-2026-84649 Published on September 2, 2026
In Stapler 1839.ved17667b_a_eb_5 through 2107.v8dfcb_e8ed317 (both inclusive), except 2088.2093.vd7c3e58008a_6, included in Jenkins 2.447 through 2.579 (both inclusive), LTS 2.452.1 through 2.568.2 (both inclusive), an HTTP endpoint serving dynamically generated JavaScript resources embeds the user's cross-site request forgery (CSRF) token (crumb) as a string literal, allowing attackers with control over a page hosted on the same site as Jenkins to obtain a valid crumb for the targeted user's session and perform actions on their behalf.
Vulnerability Analysis
CVE-2026-84649 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
What is a Session Riding Vulnerability?
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request. When a web server is designed to receive a request from a client without any mechanism for verifying that it was intentionally sent, then it might be possible for an attacker to trick a client into making an unintentional request to the web server which will be treated as an authentic request. This can be done via a URL, image load, XMLHttpRequest, etc. and can result in exposure of data or unintended code execution.
CVE-2026-84649 has been classified to as a Session Riding vulnerability or weakness.
Products Associated with CVE-2026-84649
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Affected Versions
Jenkins Project Jenkins:- Version 2.580 and below * is unaffected.
- Before 2.447 is unaffected.
- Version 2.568.3 and below 2.568.* is unaffected.