PT-2026-44146 · Symfony · Symfony

CVE-2026-45133 · Published 2026-05-21 · Updated 2026-07-17

Positive Technologies (AI Summary)

CVSS v4.0

8.2

High

Base vector

AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Name of the Vulnerable Software and Affected Versions Symfony versions prior to 5.4.21

Description The SymfonyComponentYamlParser entry point for parsing YAML strings into PHP values via Yaml::parse() lacks a depth limit for recursion. When processing attacker-controlled input, deeply nested mappings or sequences cause the block-level Parser::parseBlock() and inline Inline::parseSequence() or Inline::parseMapping() parsers to recurse indefinitely. This leads to PHP stack exhaustion and crashes the worker process.

Recommendations Update to version 5.4.21 or later. As a temporary mitigation, restrict the use of Yaml::parse() and Yaml::parseFile() with untrusted user input.

Exploit

Fix

DoS

Uncontrolled Recursion

XML Entity Expansion

Weakness Enumeration

CWE-674

CWE-1333

CWE-776

Related Identifiers

CVE-2026-45133

GHSA-C2P3-7M5P-CV8X

Affected Products

Symfony

References · 21

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45133.json · Exploit
• 🔥 https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/yaml/CVE-2026-45133.yaml · Exploit
• 🔥 https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45133.yaml · Exploit
• https://github.com/symfony/symfony/security/advisories/GHSA-c2p3-7m5p-cv8x · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-45133 · Security Note
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-45133 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-45133 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-45133 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-45133 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-45133 · Security Note
• https://osv.dev/vulnerability/GHSA-c2p3-7m5p-cv8x · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-45133 · Vendor Advisory
• https://github.com/symfony/symfony/releases/tag/v7.4.12 · Note
• https://github.com/symfony/symfony/releases/tag/v6.4.40 · Note
• https://github.com/symfony/symfony/releases/tag/v5.4.52 · Note