How severe is CVE-2026-45065?

No CVSS score has been assigned to CVE-2026-45065 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-45065?

CVE-2026-45065 affects the following packages: symfony/routing (Packagist), symfony/routing (Packagist), symfony/routing (Packagist), symfony/routing (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-45065?

Update symfony/routing to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45065 is resolved across your whole dependency graph.

How do I detect CVE-2026-45065 in my Packagist dependencies?

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

How do I mitigate CVE-2026-45065 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-2026-45065 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-45065 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-2026-45065?

CVE-2026-45065 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 26th 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-2026-45065?

CVE-2026-45065 is classified as CWE-185 (CWE-185), Open Redirect (CWE-601). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-45065 published, and has it been updated?

CVE-2026-45065 was published on July 14, 2026 and was last updated on August 12, 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

CVE-2026-45065 — routing

Fix: symfony/symfony@bcf487c

CVE-2026-45065 is a CWE-185 vulnerability in symfony/routing. A fix is available for symfony/routing — see the affected versions and patch details below.

Symfony: UrlGenerator Route-Requirement Bypass via Unanchored Regex Alternation → Off-Site //host URL Injection

Also known asGHSA-72xp-p242-47p9

Published

Jul 14, 2026

Updated

Aug 12, 2026

Affected

8 pkgs

Patched

8 / 8

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45065.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs26th percentile — riskier than 26% of all scored CVEsHighest risk

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

Real-World Exposure

8 pkgs affected

🐘symfony/routing🐘symfony/routing🐘symfony/routing🐘symfony/routing🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony

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

Symfony routes can declare a requirements regex per path parameter, e.g. a route /{_locale}/blog with requirements: { _locale: 'en|fr|de' }. The Twig path() / url() helpers (backed by UrlGenerator) validate supplied parameter values against that regex before building the URL.

UrlGenerator constructs the validation pattern as '#^'.$req.'$#', where $req is the raw requirement string. For a requirement expressed as an alternation, e.g. _locale: 'ar|bg|...|vi|...|zh_CN' (very common), ^ and $ anchor only the first and last alternatives, so any middle alternative matches as an unanchored substring. A value like /evil.com satisfies the requirement (because it contains vi), and the generated path becomes //evil.com/...: a protocol-relative URL the browser navigates off-site.

Resolution

The UrlGenerator class now wraps the requirement in a non-capturing group so the ^ and $ anchors apply to the whole alternation.

The patch for this issue is available here for branch 5.4.

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

Affected Packages

8 total 8 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/routing`	all versions	5.4.52`composer require symfony/routing:^5.4.52`
🐘Packagist	`symfony/routing`	≥ 6.0.0&&< 6.4.40	6.4.40`composer require symfony/routing:^6.4.40`
🐘Packagist	`symfony/routing`	≥ 7.0.0&&< 7.4.12	7.4.12`composer require symfony/routing:^7.4.12`
🐘Packagist	`symfony/routing`	≥ 8.0.0&&< 8.0.12	8.0.12`composer require symfony/routing:^8.0.12`
🐘Packagist	`symfony/symfony`	all versions	5.4.52`composer require symfony/symfony:^5.4.52`
🐘Packagist	`symfony/symfony`	≥ 6.0.0&&< 6.4.40	6.4.40`composer require symfony/symfony:^6.4.40`

Affected Products

1 product · 4 configurations

Application

symfonysensiolabs

≥ 8.0.0 && < 8.0.12

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/routing, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/routing to 5.4.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45065 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

### Description Symfony routes can declare a requirements regex per path parameter, e.g. a route `/{_locale}/blog` with `requirements: { _locale: 'en|fr|de' }`. The Twig `path()` / `url()` helpers (backed by `UrlGenerator`) validate supplied parameter values against that regex before building the URL. UrlGenerator constructs the validation pattern as `'#^'.$req.'$#'`, where `$req` is the raw requirement string. For a requirement expressed as an alternation, e.g. `_locale: 'ar|bg|...|vi|...|zh_CN'` (very common), `^` and `$` anchor only the first and last alternatives, so any middle alternati