X509Authenticator · Authentication Bypass by Spoofing
Affects symfonySource GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 7.7 High · fixed in 5.4.56 : patch symfony soon.
Data as of 6 Nov 2026, 05:04 UTC
Thin evidence
One scorer or none| CNA (Checkmarx) | CVSS 4.0 | 7.7 |
|---|
- Patch
- Available – fixed in 5.4.56
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 4 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10symfonypkg:deb/ubuntu/symfony?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu Pro 24.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available in Symfony versions 5.4.56, 6.4.50, 7.4.23, and 8.1.11 that corrects the DN parsing logic to prevent spoofing. Users should upgrade to these fixed versions to mitigate the vulnerability. Applications that use per-attribute user keys or have CA-validated subject generation or validation are not affected and may not require immediate action.
Description
Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11 contain an authentication bypass vulnerability in X509Authenticator and X509AuthenticationListener. The flaw allows an attacker with a certificate from the trusted CA who can manipulate the Common Name (CN) in the certificate's Subject DN to authenticate as any user, including privileged users. This issue stems from improper parsing of the Subject DN string, where escaped separators inside attribute values are misinterpreted, enabling spoofing. The vulnerability is a follow-up to an incomplete fix for CVE-2026-45063. The fix involves correctly splitting and unescaping the DN into Relative Distinguished Names (RDNs) before attribute extraction. Deployments using per-attribute user keys or those with CA-validated subjects are not affected.