CVE-2026-45305

Symfony: YAML Parser ReDoS via Catastrophic Backtracking in Parser::cleanup() Regex

HIGH

7.5

CVSS Score

Published: July 14, 2026 at 06:50 PM UTC

Updated: July 15, 2026 at 03:14 PM UTC

3 products affected across 2 vendorsSymfonySymfonyYaml

Using symfony by symfony?

Get instant alerts when new vulnerabilities affect symfony - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

HIGH7.5

Exploit prediction

EPSS 0.7%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Symfony · Sensiolabsdrupal

95%

v < 5.4.526.0.0 ≤ v < 6.4.407.0.0 ≤ v < 7.4.128.0.0 ≤ v < 8.0.12

Affected range stops below 5.4.52, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.4.40, so it looks safe — our inference, not a vendor statement

Affected range stops below 7.4.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.0.12, so it looks safe — our inference, not a vendor statement

Symfony · Symfonycomposer

60%

v < 5.4.52v < 6.4.40v < 7.4.12v < 8.0.12

Affected range stops below 5.4.52, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.4.40, so it looks safe — our inference, not a vendor statement

Affected range stops below 7.4.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.0.12, so it looks safe — our inference, not a vendor statement

Yaml · Symfony

60%

v < 5.4.52v < 6.4.40v < 7.4.12v < 8.0.12

Affected range stops below 5.4.52, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.4.40, so it looks safe — our inference, not a vendor statement

Affected range stops below 7.4.12, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.0.12, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (6)

x_refsource_CONFIRMPatchVendor Advisory

Source: cverecord

https://github.com/symfony/symfony/security/advisories/GHSA-9frc-8383-795m

x_refsource_MISCPatch

Source: cverecord

https://github.com/symfony/symfony/commit/9749cd43c5e09b3735093623670b21b9d8a056cb

x_refsource_MISCProductRelease Notes

Source: cverecord

https://github.com/symfony/symfony/releases/tag/v5.4.52

x_refsource_MISCProductRelease Notes

Source: cverecord

https://github.com/symfony/symfony/releases/tag/v6.4.40

x_refsource_MISCProductRelease Notes

Source: cverecord

https://github.com/symfony/symfony/releases/tag/v7.4.12

x_refsource_MISCProductRelease Notes

Source: cverecord

https://github.com/symfony/symfony/releases/tag/v8.0.12

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-1333

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create account Sign in

Free plan, no card