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CVE-2026-118513VulnerabilityPublished Updated

X509Authenticator · Authentication Bypass by Spoofing

Affects symfonySource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-118513· High 7.7

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

CVSS 4.0 base score
7.7High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Checkmarx)CVSS 4.07.7
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
Ubuntu 26.10symfonypkg:deb/ubuntu/symfony?arch=source&distro=stonkingOther threatsAffected
  • 7.4.7+dfsg-1ubuntu1 – 7.4.16+dfsg-1ubuntu2
6 affected builds
Fixed in–
Ubuntu 26.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=resoluteOther threatsAffected
  • 6.4.24+dfsg-1 – 7.4.7+dfsg-1ubuntu1
4 affected builds
Fixed in–
Ubuntu Pro 24.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/nobleOther threatsAffected
  • 5.4.23+dfsg-1ubuntu1 – 6.4.5+dfsg-3ubuntu3+esm1
5 affected builds
Fixed in–
Ubuntu Pro 22.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/jammyOther threatsAffected
  • =5.2.6+dfsg-1ubuntu7
  • =5.4.4+dfsg-1ubuntu8
  • =5.4.4+dfsg-1ubuntu8+esm1
Fixed in–
Ubuntu Pro 20.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/focalOther threatsAffected
  • 4.3.4+dfsg-1ubuntu1 – 4.3.8+dfsg-1ubuntu1+esm2
4 affected builds
Fixed in–
Ubuntu Pro 18.04 LTSsymfonypkg:deb/ubuntu/symfony?arch=source&distro=esm-apps/bionicOther threatsAffected
  • 2.8.7+dfsg-1.3ubuntu1 – 3.4.6+dfsg-1ubuntu0.1+esm2
6 affected builds
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.

References

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