Bug 2500234 (CVE-2026-15747) - CVE-2026-15747 Mojolicious: Mojolicious: Information disclosure via BREACH compression oracle
Summary: CVE-2026-15747 Mojolicious: Mojolicious: Information disclosure via BREACH co...
Keywords:
Status: NEW
Alias: CVE-2026-15747
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2500952 2500953
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-14 18:09 UTC by OSIDB Bzimport
Modified: 2026-07-15 14:17 UTC (History)
0 users

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)

Description OSIDB Bzimport 2026-07-14 18:09:44 UTC 
Mojolicious versions from 4.59 before 9.48 for Perl expose a stable representation of the session CSRF token to a BREACH compression oracle.

_csrf_token generates and caches one token per session and returns the same value on every call, and _csrf_field places that value in a hidden `csrf_token` input. When a response carrying the token also echoes attacker-controlled input and is gzip-compressed, the chosen values and the resulting compressed lengths form a BREACH oracle.

An attacker able to query it can recover the token and pass csrf_protect validation.
Note You need to log in before you can comment on or make changes to this bug.