CVE-2026-45305: Symfony is a PHP framework for web and console applications and a set of reusable PHP components

This month

HIGH 7.5REMOTEUPGRADE

CVE-2026-45305 is a high-severity flaw (CVSS 7.5) affecting symfony. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-1333
Published	2026-07-14
Last modified	2026-07-15

Publisher (CNA): GitHub, Inc. · Vendor: sensiolabs

Last updated 2026-07-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-14 19:17 UTCPublished CVE record published
2026-07-15 14:57 UTCUpdated Record last modified

sensiolabs symfony UPGRADE

Affected: < 5.4.52 · >= 6.0.0 and < 6.4.40 · >= 7.0.0 and < 7.4.12 · >= 8.0.0 and < 8.0.12

Fixed in: 5.4.52, 6.4.40, 7.4.12, 8.0.12

Safe to downgrade to: a release before 6.0.0

1. Check installed version

apt-cache policy symfony || rpm -q symfony || symfony --version

2. UPGRADE to 5.4.52 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade symfony

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade symfony

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 6.0.0 (Debian / Ubuntu)

apt-cache madison symfony sudo apt install symfony=<VERSION_BEFORE_6.0.0> sudo apt-mark hold symfony

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list symfony sudo dnf downgrade symfony-<VERSION_BEFORE_6.0.0> sudo dnf versionlock add symfony

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-45305?

symfony: upgrade to 5.4.52, 6.4.40, 7.4.12, 8.0.12. Exact commands for each OS are on this page.

Is CVE-2026-45305 being exploited?

CVE-2026-45305 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-45305 affect?

CVE-2026-45305 affects symfony. Severity is high (CVSS 7.5). 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 fo

How urgent is CVE-2026-45305?

Priority 44/100. High severity; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2026-45073 HIGH 7.3 UPGRADE Symfony is a PHP framework for web and console applications and a set of reusable PHP components
CVE-2026-45064 MEDIUM 6.1 UPGRADE Symfony is a PHP framework for web and console applications and a set of reusable PHP components
CVE-2026-48761 MEDIUM 6.1 UPGRADE Symfony is a PHP framework for web and console applications and a set of reusable PHP components
CVE-2026-45756 HIGH 7.5 UPGRADE Symfony is a PHP framework for web and console applications and a set of reusable PHP components
CVE-2026-45754 MEDIUM 5.3 UPGRADE Symfony is a PHP framework for web and console applications and a set of reusable PHP components

References

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