How severe is CVE-2018-11406?

CVE-2018-11406 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2018-11406?

CVE-2018-11406 affects the following packages: symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/security-bundle (Packagist), symfony/security-bundle (Packagist), symfony/security-bundle (Packagist), and 12 more. Ecosystems affected: Packagist.

How do I fix CVE-2018-11406?

Update symfony/symfony to 2.7.48 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-11406 is resolved across your whole dependency graph.

How do I detect CVE-2018-11406 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/symfony, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2018-11406 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2018-11406 actively exploited in the wild?

No public exploit code has been indexed for CVE-2018-11406 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2018-11406?

CVE-2018-11406 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 55th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2018-11406?

CVE-2018-11406 is classified as Cross-Site Request Forgery (CSRF) (CWE-352). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2018-11406 published, and has it been updated?

CVE-2018-11406 was published on June 13, 2018 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

HIGH severity

CVE-2018-11406 — symfony

HIGHFix: symfony/symfony@319e1bd

CVE-2018-11406 is a high-severity (CVSS 8.8) Cross-Site Request Forgery (CSRF) vulnerability in symfony/symfony. A fix is available for symfony/symfony — see the affected versions and patch details below.

Symfony CSRF Token Fixation

Also known asGHSA-g4g7-q726-v5hg

Published

Jun 13, 2018

Updated

Oct 24, 2026

Affected

20 pkgs

Patched

20 / 20

Exploits

None indexed

Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs55th percentile — riskier than 55% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

20 pkgs affected

🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/security-bundle🐘symfony/security-bundle🐘symfony/security-bundle+12 more

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

An issue was discovered in the Security component in Symfony 2.7.x before 2.7.48, 2.8.x before 2.8.41, 3.3.x before 3.3.17, 3.4.x before 3.4.11, and 4.0.x before 4.0.11. By default, a user's session is invalidated when the user is logged out. This behavior can be disabled through the invalidate_session option. In this case, CSRF tokens were not erased during logout which allowed for CSRF token fixation.

Affected Packages

20 total 20 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/symfony`	≥ 2.7.0&&< 2.7.48	2.7.48`composer require symfony/symfony:^2.7.48`
🐘Packagist	`symfony/symfony`	≥ 2.8.0&&< 2.8.41	2.8.41`composer require symfony/symfony:^2.8.41`
🐘Packagist	`symfony/symfony`	≥ 3.0.0&&< 3.3.17	3.3.17`composer require symfony/symfony:^3.3.17`
🐘Packagist	`symfony/symfony`	≥ 3.4.0&&< 3.4.11	3.4.11`composer require symfony/symfony:^3.4.11`
🐘Packagist	`symfony/symfony`	≥ 4.0.0&&< 4.0.11	4.0.11`composer require symfony/symfony:^4.0.11`
🐘Packagist	`symfony/security-bundle`	≥ 2.7.0&&< 2.7.48	2.7.48`composer require symfony/security-bundle:^2.7.48`

Affected Products

2 products · 6 configurations

debian linuxdebian

1 version

9.0

Application

symfonysensiolabs

≥ 4.0.0 && < 4.0.11

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/symfony, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/symfony to 2.7.48 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-11406 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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