CVE-2026-118513: sensiolabs symfony · Authentication Bypass by Spoofing
Affects sensiolabs symfonySource CVE Database V5
Mentioned vulnerabilities
Not known to be exploited · CVSS 7.7 High · fixed in 8.1.11 : patch sensiolabs symfony soon.
Data as of 4 Nov 2026, 12:59 UTC
Thin evidence
One scorer or none| CNA (Checkmarx) | CVSS 4.0 | 7.7 |
|---|
- Patch
- Available – fixed in 8.1.11, 7.4.23, 6.4.50 +1
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 4 Nov 2026.
What to do
Upgrade symfony and symfony/security-http to 8.1.11, 7.4.23, 6.4.50 or 5.4.56.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| symfonysymfony/security-http | Affected
| Fixed in
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| symfonysymfony/security-http | Affected
| Fixed in
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| symfonysymfony/security-http | Affected
| Fixed in
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| symfonysymfony/security-http | Affected
| Fixed in
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Packagistsymfony/security-httppkg:composer/symfony/security-httpOther threats | Affected
| Fixed in
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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. Users should upgrade to these or later versions to remediate this vulnerability. Applications that use per-attribute user keys (e.g., SSL_CLIENT_S_DN_Email) or whose certificate authorities generate or validate the subject DN are not affected. No additional mitigations are specified beyond applying the official patches.
Description
Authentication bypass by spoofing in X509Authenticator and X509AuthenticationListener of 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 allows an attacker holding a certificate from the application's trusted CA who can influence the CN to authenticate as an arbitrary user of the application, including a privileged one, following an incomplete fix for CVE-2026-45063. X509Authenticator extracts the user identifier from the Subject DN (Distinguished Name) that the web server passes in $_SERVER['SSL_CLIENT_S_DN']. The fix for CVE-2026-45063 anchored that extraction to an RDN (Relative Distinguished Name) boundary, but the regular expression used was not escape-aware. The expression runs against an already serialized DN, so it cannot tell an RDN separator from a separator character that occurs inside a value. Under RFC 2253, used by Apache and by nginx's $ssl_client_s_dn, a comma inside a value is escaped as \, and the expression reads it as a separator regardless. RFC 2253 also does not treat / as a separator, so it leaves it bare inside a value, while the expression treats every / as one. The legacy X509_NAME_oneline() format, used by Apache's LegacyDNStringFormat and by nginx's $ssl_client_s_dn_legacy, is the mirror image: it escapes / as \/ and leaves , bare. In that format, a certificate with no emailAddress attribute, or whose poisoned CN precedes it, authenticates as the smuggled address. To cover both RFC 2253 and the legacy X509_NAME_oneline() format, X509Authenticator and X509AuthenticationListener now split the DN into RDNs before looking for the attribute, instead of matching the attribute against the serialized string. They select the separator from the serialization, split on unescaped occurrences of that separator only, unescape each RDN afterwards with the rules of its format, and require the attribute to span a whole RDN. The accepted value grammar is unchanged. Applications that pass a per-attribute user key (such as SSL_CLIENT_S_DN_Email) and deployments whose CA generates or validates the subject are not affected by this vulnerability.