CVE-2026-15747
BREACH oracle allows recovery of session CSRF token in Mojolicious apps
Is CVE-2026-15747 being exploited?
Not confirmed. CVE-2026-15747 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.26% probability of exploitation in the next 30 days.
How severe is CVE-2026-15747?
CVE-2026-15747 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-15747?
Yes. A fix has been recorded for CVE-2026-15747. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-15747 affect?
CVE-2026-15747 affects Mojolicious (Perl) >=4.59 and <9.48, Web applications using Mojolicious csrf_token/_csrf_field. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-15747?
Upgrade to Mojolicious 9.48+ or disable response compression / avoid echoing attacker-controlled input.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Recover session CSRF token via BREACH on gzip-compressed responses, bypass CSRF protection and perform unauthorized actions as victims.
Immediate action required
- affected>= 4.59 and < 9.48
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.