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CVE-2026-45305: Symfony's YAML Parser has a ReDoS via Catastrophic Backtracking in Parser::cleanup() Regex

low Affects symfony/symfony, symfony/yaml. Feed 2026.10.29.1, updated 2026-10-28; published ; advisory modified .

Symfony's YAML Parser has a ReDoS via Catastrophic Backtracking in Parser::cleanup() Regex

Package
symfony/symfony Composer
Affected versions
<5.4.52 or >=6.0.0 and <6.4.40 or >=7.0.0 and <7.4.12 or >=8.0.0 and <8.0.12 or >=2.0.0 and <3.0.0 or >=3.0.0 and <4.0.0 or >=4.0.0 and <5.0.0 or >=5.0.0 and <5.1.0 or >=5.1.0 and <5.2.0 or >=5.2.0 and <5.3.0 or >=5.3.0 and <5.4.0 or >=5.4.0 and <5.4.52 or >=6.0.0 and <6.1.0 or >=6.1.0 and <6.2.0 or >=6.2.0 and <6.3.0 or >=6.3.0 and <6.4.0 or >=6.4.0 and <6.4.40 or >=7.0.0 and <7.1.0 or >=7.1.0 and <7.2.0 or >=7.2.0 and <7.3.0 or >=7.3.0 and <7.4.0 or >=7.4.0 and <7.4.12
Fixed in
5.4.52, 6.4.40, 7.4.12, 8.0.12
Severity
low
Exploitation
not on CISA KEV · EPSS 1% (52.4th percentile)
Published
2026-05-27
Source
osv.dev

References

Symfony's YAML Parser has a ReDoS via Catastrophic Backtracking in Parser::cleanup() Regex

Package
symfony/yaml Composer
Affected versions
<5.4.52 or >=6.0.0 and <6.4.40 or >=7.0.0 and <7.4.12 or >=8.0.0 and <8.0.12 or >=2.0.0 and <3.0.0 or >=3.0.0 and <4.0.0 or >=4.0.0 and <5.0.0 or >=5.0.0 and <5.1.0 or >=5.1.0 and <5.2.0 or >=5.2.0 and <5.3.0 or >=5.3.0 and <5.4.0 or >=5.4.0 and <5.4.52 or >=6.0.0 and <6.1.0 or >=6.1.0 and <6.2.0 or >=6.2.0 and <6.3.0 or >=6.3.0 and <6.4.0 or >=6.4.0 and <6.4.40 or >=7.0.0 and <7.1.0 or >=7.1.0 and <7.2.0 or >=7.2.0 and <7.3.0 or >=7.3.0 and <7.4.0 or >=7.4.0 and <7.4.12
Fixed in
5.4.52, 6.4.40, 7.4.12, 8.0.12
Severity
low
Exploitation
not on CISA KEV · EPSS 1% (52.4th percentile)
Published
2026-05-27
Source
osv.dev

References

CWE-1333
NVD recordsymfony/symfony advisoriessymfony/yaml advisories

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