How severe is CVE-2018-11408?

CVE-2018-11408 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2018-11408?

CVE-2018-11408 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 2 more. Ecosystems affected: Packagist.

How do I fix CVE-2018-11408?

Update symfony/symfony to 2.7.48 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-11408 is resolved across your whole dependency graph.

How do I detect CVE-2018-11408 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-2018-11408 if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is CVE-2018-11408 actively exploited in the wild?

No public exploit code has been indexed for CVE-2018-11408 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-2018-11408?

CVE-2018-11408 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 66th 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-2018-11408?

CVE-2018-11408 is classified as Open Redirect (CWE-601). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2018-11408 published, and has it been updated?

CVE-2018-11408 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

MEDIUM severity

CVE-2018-11408 — symfony

MEDIUMFix: symfony/symfony@b20e835

CVE-2018-11408 is a medium-severity (CVSS 6.1) Open Redirect vulnerability in symfony/symfony. A fix is available for symfony/symfony — see the affected versions and patch details below.

Symfony Open Redirect

Also known asGHSA-7hwc-2cq4-6x2w

Published

Jun 13, 2018

Updated

Oct 24, 2026

Affected

10 pkgs

Patched

10 / 10

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs66th percentile — riskier than 66% 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

10 pkgs affected

🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/security-bundle🐘symfony/security-bundle🐘symfony/security-bundle+2 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

The security handlers in the Security component in Symfony in 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 have an Open redirect vulnerability when security.http_utils is inlined by a container. NOTE: this issue exists because of an incomplete fix for CVE-2017-16652.

Affected Packages

10 total 10 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`	≥ 3.3.0&&< 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

8.0

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-2018-11408 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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