High 8.2Published Jul 14, 2026

CVE-2026-45133Symfony: [Yaml] Harden the parser when handling untrusted input

Updated under an hour ago (Oct 26, 2026, 5:50 PM ET)

Does this affect you?

It affects symfony and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for symfony

Exploited in the last 30 days

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, when the parser is exposed to attacker-controlled input, deeply nested mappings or sequences cause both the block-level (Parser::parseBlock()) and inline (Inline::parseSequence() / Inline::parseMapping()) parsers to recurse without a depth limit. A crafted document exhausts the PHP stack and crashes the worker. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.

CVSS: 8.2 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness (CWE): CWE-674, CWE-776, CWE-1333
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

symfony symfony symfony:symfony (from the name)	before 5.4.52; from 6.0.0-BETA1, < 6.4.40; from 7.0.0-BETA1, < 7.4.12; from 8.0.0-BETA1, < 8.0.12	CNA record
sensiolabs symfony sensiolabs:symfony	before 5.4.52; from 6.0.0 before 6.4.40; from 7.0.0 before 7.4.12; from 8.0.0 before 8.0.12	NVD

References

References

https://github.com/symfony/symfony/security/advisories/GHSA-c2p3-7m5p-cv8x	x-refsource-confirm, patch, vendor-advisory
https://github.com/symfony/symfony/releases/tag/v5.4.52	x-refsource-misc, product, release-notes
https://github.com/symfony/symfony/releases/tag/v6.4.40	x-refsource-misc, product, release-notes
https://github.com/symfony/symfony/releases/tag/v7.4.12	x-refsource-misc, product, release-notes
https://github.com/symfony/symfony/releases/tag/v8.0.12	x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.