Symfony is a widely used PHP web framework; this auth-bypass allows certificate-based impersonation and impacts deployed apps using X.509 client auth.
CVE-2026-45063
Auth bypass via X.509 DN parsing in Symfony enabling certificate-based impersonation
Is CVE-2026-45063 being exploited?
Not confirmed. CVE-2026-45063 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 0.37% probability of exploitation in the next 30 days.
How severe is CVE-2026-45063?
CVE-2026-45063 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-2026-45063?
Yes. A fix has been recorded for CVE-2026-45063. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-45063 affect?
CVE-2026-45063 affects Symfony <5.4.52, Symfony <6.4.40, Symfony <7.4.12, Symfony <8.0.12, and 1 further product or version. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-45063?
Upgrade to patched Symfony versions; revoke suspicious client certs; audit client-cert auth.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authentication bypass: attacker with a trusted client cert can impersonate any user by placing emailAddress in another DN field.
Immediate action required
- affected< 5.4.52
- affected>= 6.0.0-BETA1 and < 6.4.40
- affected>= 7.0.0-BETA1 and < 7.4.12
- affected>= 8.0.0-BETA1 and < 8.0.12
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.