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.
csrftoken generates and caches one token per session and returns the same value on every call, and csrffield 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.
Package Versions Affected
Automatically patch vulnerabilities without upgrading
CVSS Version



Related Resources
References
http://www.openwall.com/lists/oss-security/2026/07/14/16, https://cpan.org/modules, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/15xxx/CVE-2026-15747.json, https://metacpan.org/release/SRI/Mojolicious-9.48/changes, https://nvd.nist.gov/vuln/detail/CVE-2026-15747, https://github.com/mojolicious/mojo/commit/01921fbbbbeca2d1397e082d4a647f9b84c24e27.patch, https://github.com/mojolicious/mojo