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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

• CVE-2026-45065: 0.35% estimated exploitation activity in the next 30 days; percentile 28.50 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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|...|zhCN' (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…

Published by the source

27 May 2026, 16:55 UTC

Last modified by the source

27 May 2026, 16:55 UTC

Source last checked

26 Oct 2026, 14:40 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-72xp-p242-47p9

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# Patch Next advisory brief: CVE-2026-45065

Advisory: Symfony has a UrlGenerator Route-Requirement Bypass via Unanchored Regex Alternation → Off-Site //host URL Injection
IDs: CVE-2026-45065, GHSA-72xp-p242-47p9
Record: https://patchnext.com/advisories/cve-2026-45065 (revision 1, source checked 26 Oct 2026, 14:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: symfony/symfony 8.0.12, 7.4.12, 6.4.40, 5.4.52; symfony/routing 8.0.12, 7.4.12, 6.4.40, 5.4.52. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist symfony/symfony: affected < 5.4.52; >= 6.0.0, < 6.4.40; >= 7.0.0, < 7.4.12; >= 8.0.0, < 8.0.12; fixed in 8.0.12, 7.4.12, 6.4.40, 5.4.52
- Packagist symfony/routing: affected < 5.4.52; >= 6.0.0, < 6.4.40; >= 7.0.0, < 7.4.12; >= 8.0.0, < 8.0.12; fixed in 8.0.12, 7.4.12, 6.4.40, 5.4.52

## Suggested inspection (read-only)
- Packagist symfony/symfony: check the installed version with your package manager.
- Packagist symfony/routing: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on symfony/symfony, symfony/routing.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-72xp-p242-47p9 (GitHub-reviewed advisory GHSA-72xp-p242-47p9 lists affected ranges: Packagist symfony/routing >=0 =6.0.0 =7.0.0 =8.0.0 =0 =6.0.0 =7.0.0 =8.0.0 <8.0.12)

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