CVE-2026-15747

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.

Scoring

Severity
CRITICAL
CVSS base score
9.1
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS probability
0.26%
CWE
CWE-204, CWE-352
Published
2026-07-14
Last modified
2026-07-15

Affected products

Weakness type

Related vulnerabilities

Markdown version · Browse all CVEs