CVE-2026-45063: Sensiolabs Symfony authentication bypass (CVSS 9.1)

Description

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.52, 6.4.40, 7.4.12, and 8.0.12, X509Authenticator extracts the user identifier from $_SERVER['SSL_CLIENT_S_DN'] with an unanchored regex that matches emailAddress= anywhere in the distinguished name, allowing an attacker with a trusted certificate containing emailAddress=victim inside another RDN value such as CN to authenticate as the victim. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Sensiolabs Symfony≥ 6.0.0 < 6.4.40 · ≥ 7.0.0 < 7.4.12 · ≥ 8.0.0 < 8.0.12 · < 5.4.52

Remediation

Fixed in

Sensiolabs Symfony≥ 6.4.40

Patch & vendor advisories

References

https://github.com/symfony/symfony/commit/59ef484029601a7af06f5e06c6ed921fdcea5a0dPatch
https://github.com/symfony/symfony/releases/tag/v5.4.52ProductRelease Notes
https://github.com/symfony/symfony/releases/tag/v6.4.40ProductRelease Notes
https://github.com/symfony/symfony/releases/tag/v7.4.12ProductRelease Notes
https://github.com/symfony/symfony/releases/tag/v8.0.12ProductRelease Notes
https://github.com/symfony/symfony/security/advisories/GHSA-ph86-p8f6-f9r2PatchVendor Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-45063 being actively exploited?

CVE-2026-45063 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.37%.

How severe is CVE-2026-45063?

CVE-2026-45063 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.37% probability of exploitation.

Which products are affected by CVE-2026-45063?

Affected products include Sensiolabs Symfony.

How do I fix CVE-2026-45063?

Upgrade affected software to a fixed version, for example Sensiolabs Symfony 6.4.40 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-45063 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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