What is GHSA-ph86-p8f6-f9r2?

### Description `X509Authenticator` implements client-certificate (mTLS) authentication: the web server validates the client's certificate against a trusted CA, then passes the certificate's Subject DN (Distinguished Name: a string like `CN=Alice,O=Example,emailAddress=alice@example.com`) to Symfony via `$_SERVER['SSL_CLIENT_S_DN']`. Symfony extracts the user identifier from that string. The extraction uses an **unanchored** regex that matches `emailAddress=` anywhere in the DN string: including inside the *value* of a different RDN (Relative Distinguished Name: one `key=value` component of

How severe is GHSA-ph86-p8f6-f9r2?

No CVSS score has been assigned to GHSA-ph86-p8f6-f9r2 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-ph86-p8f6-f9r2?

GHSA-ph86-p8f6-f9r2 affects the following packages: symfony/security-http (Packagist), symfony/security-http (Packagist), symfony/security-http (Packagist), symfony/security-http (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist). Ecosystems affected: Packagist.

How do I fix GHSA-ph86-p8f6-f9r2?

Update symfony/security-http to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ph86-p8f6-f9r2 is resolved across your whole dependency graph.

How do I detect GHSA-ph86-p8f6-f9r2 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/security-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-ph86-p8f6-f9r2 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is GHSA-ph86-p8f6-f9r2 actively exploited in the wild?

No public exploit code has been indexed for GHSA-ph86-p8f6-f9r2 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-ph86-p8f6-f9r2?

GHSA-ph86-p8f6-f9r2 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 28th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-ph86-p8f6-f9r2?

GHSA-ph86-p8f6-f9r2 is classified as CWE-290 (CWE-290). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-ph86-p8f6-f9r2 published, and has it been updated?

GHSA-ph86-p8f6-f9r2 was published on May 27, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

Symfony Vulnerable to Identity Spoofing via Unanchored DN Regex in X509AuthenticatorGHSA-ph86-p8f6-f9r2

Fix: symfony/symfony@ccb3f72

GHSA-ph86-p8f6-f9r2 is a CWE-290 vulnerability in symfony/security-http. A fix is available for symfony/security-http — see the affected versions and patch details below.

Also known asCVE-2026-45063

Published

May 27, 2026

Updated

Sep 10, 2026

Affected

8 pkgs

Patched

8 / 8

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-ph86-p8f6-f9r2.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs28th percentile — riskier than 28% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

8 pkgs affected

🐘symfony/security-http🐘symfony/security-http🐘symfony/security-http🐘symfony/security-http🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

X509Authenticator implements client-certificate (mTLS) authentication: the web server validates the client's certificate against a trusted CA, then passes the certificate's Subject DN (Distinguished Name: a string like CN=Alice,O=Example,[email protected]) to Symfony via $_SERVER['SSL_CLIENT_S_DN']. Symfony extracts the user identifier from that string.

The extraction uses an unanchored regex that matches emailAddress= anywhere in the DN string: including inside the value of a different RDN (Relative Distinguished Name: one key=value component of the DN), such as CN. An attacker who can obtain a certificate from a trusted CA with a free-text CN can smuggle emailAddress=victim@target inside the CN value and be authenticated as the victim.

Resolution

The X509Authenticator now uses a regex that anchors the match to an RDN boundary (start of string, or following a , / / separator).

The patch for this issue is available here for branch 5.4.

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Affected Packages

8 total 8 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/security-http`	all versions	5.4.52`composer require symfony/security-http:^5.4.52`
🐘Packagist	`symfony/security-http`	≥ 6.0.0-BETA1&&< 6.4.40	6.4.40`composer require symfony/security-http:^6.4.40`
🐘Packagist	`symfony/security-http`	≥ 7.0.0-BETA1&&< 7.4.12	7.4.12`composer require symfony/security-http:^7.4.12`
🐘Packagist	`symfony/security-http`	≥ 8.0.0-BETA1&&< 8.0.12	8.0.12`composer require symfony/security-http:^8.0.12`
🐘Packagist	`symfony/symfony`	all versions	5.4.52`composer require symfony/symfony:^5.4.52`
🐘Packagist	`symfony/symfony`	≥ 6.0.0-BETA1&&< 6.4.40	6.4.40`composer require symfony/symfony:^6.4.40`

Affected Products

1 product · 4 configurations

Application

symfonysensiolabs

≥ 8.0.0 && < 8.0.12

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/security-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/security-http to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ph86-p8f6-f9r2 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Description `X509Authenticator` implements client-certificate (mTLS) authentication: the web server validates the client's certificate against a trusted CA, then passes the certificate's Subject DN (Distinguished Name: a string like `CN=Alice,O=Example,[email protected]`) to Symfony via `$_SERVER['SSL_CLIENT_S_DN']`. Symfony extracts the user identifier from that string. The extraction uses an **unanchored** regex that matches `emailAddress=` anywhere in the DN string: including inside the *value* of a different RDN (Relative Distinguished Name: one `key=value` component of

O3 Security · Impact-Aware SCA

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Symfony Vulnerable to Identity Spoofing via Unanchored DN Regex in X509AuthenticatorGHSA-ph86-p8f6-f9r2

Exploitation Status

No confirmed exploitation observed yet

EPSS Exploitation Probability

Real-World Exposure

Description

Description

Resolution

Credits

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is GHSA-ph86-p8f6-f9r2 in your dependencies?