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CVE-2026-45305

HIGH 8.7 ALL-YEARS

Published 2026-07-14 · Last modified 2026-07-15 · GitHub_M · NVD: Analyzed

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.

ELEVATED IMPACT

Severe if exploited (CVSS 8.7), but no confirmed exploitation. Patch on a normal cadence.

Exploitation likelihood

0.8%chance of exploitation in 30 days · 54th percentile

○ In CISA KEV○ Public exploit / PoC◆ SSVC: exploitation none, automatable yes

Impact if exploited

8.7CVSS 4.0 · HIGH · CNA

  • ConfidentialityNone
  • IntegrityNone
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable
  • ✓Requirements: No special attack requirements

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

No public exploit or proof-of-concept code is catalogued for this CVE (no ExploitDB, Nuclei, or CISA-KEV entry). It may still exist — search GitHub or check the references below.

Affected

Vendors Symfony Sensiolabs

Products Symfony Yaml

Weakness (CWE)

  • CWE-1333: : Inefficient Regular Expression Complexity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Known Affected Software Configurations

VendorProductVersion range
SensiolabsSymfony< 5.4.52
SensiolabsSymfony≥ 6.0.0 and < 6.4.40
SensiolabsSymfony≥ 7.0.0 and < 7.4.12
SensiolabsSymfony≥ 8.0.0 and < 8.0.12

All CVSS metrics

  • HIGH 8.7 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
  • HIGH 8.7 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
  • HIGH 7.5 v3.1 · NVD Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Patches & mitigations

Technical & other

Sources: NVD · CVE.org · EPSS