CSRF in Sri Mojolicious
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.
EPSS: 0.003 (16.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
Affected products
- Sri Mojolicious — versions 4.59
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-15747?
- CVE-2026-15747 is a critical-severity vulnerability in Sri Mojolicious, classified under Observable Response Discrepancy. CVSS score: 9.1/10. Published 2026-07-14.
- How severe is CVE-2026-15747?
- Critical severity. CVSS v3 base score is 9.1 out of 10.