High severity · published Jul 14, 2026
CVE-2026-45305
Symfony: YAML Parser ReDoS via Catastrophic Backtracking in Parser::cleanup() Regex
7.5
CVSS
0.7%
EPSS
No
On KEV
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, Symfony\Component\Yaml\Parser::cleanup() used regular expressions with overlapping quantifiers for YAML directive, comment, and document marker cleanup, allowing crafted input to make parsing hang for an arbitrarily long time. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 52% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SY
symfony · symfony
< 5.4.52; >= 6.0.0-BETA1, < 6.4.40; >= 7.0.0-BETA1, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor, NVD
YA
yaml · symfony
< 5.4.52; >= 6.0.0-BETA1, < 6.4.40; >= 7.0.0-BETA1, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45305
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45305
Patch
https://github.com/symfony/symfony/commit/9749cd43c5e09b3735093623670b21b9d8a056cb
Product
https://github.com/symfony/symfony/releases/tag/v5.4.52
Product
https://github.com/symfony/symfony/releases/tag/v6.4.40
Product
https://github.com/symfony/symfony/releases/tag/v7.4.12
Product
https://github.com/symfony/symfony/releases/tag/v8.0.12
Patch
https://github.com/symfony/symfony/security/advisories/GHSA-9frc-8383-795m
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