# CVE-2026-15747: libmojolicious-perl: Mojolicious versions from 4.59 before 9.48 for Perl expose a stable representation of the session CSRF token to a BRE...

CVE-2026-15747 is fixed in 3 products on 1 platform, first by FEDORA-2026-6F12B08313, released July 19, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-15747
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 14, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libmojolicious-perl Debian 14 | 9.48+dfsg-1 | [DEBIAN-CVE-2026-15747](https://patchblox.com/security/data/fix/linux/debian-cve-2026-15747.md) | Jul 31, 2026 |
| Linux | perl-Mojolicious Fedora 43 | 9.48-1.fc43 | [FEDORA-2026-6F12B08313](https://patchblox.com/security/data/fix/linux/fedora-2026-6f12b08313.md) | Jul 19, 2026 |
| Linux | perl-Mojolicious amzn 2023 | 9.48-2.amzn2023.0.1 | [ALAS2023-2026-3209](https://patchblox.com/security/data/fix/linux/alas2023-2026-3209.md) | Nov 7, 2026 |
| Linux | perl-Mojolicious opensuse-leap 16.0 | 9.480.0-bp160.1.1 | [OPENSUSE-SU-2026:21496-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21496-1.md) | Jul 29, 2026 |
| Linux | perl-Mojolicious sles 15.7 | 9.370.0-150700.3.3.1 | [SUSE-SU-2026:4151-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4151-1.md) | Sep 14, 2026 |
| Linux | perl-Test-Mojo Fedora 43 | 9.48-1.fc43 | [FEDORA-2026-6F12B08313](https://patchblox.com/security/data/fix/linux/fedora-2026-6f12b08313.md) | Jul 19, 2026 |
| Linux | perl-Test-Mojo amzn 2023 | 9.48-2.amzn2023.0.1 | [ALAS2023-2026-3209](https://patchblox.com/security/data/fix/linux/alas2023-2026-3209.md) | Nov 7, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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