SymfonyFramework / library · Sensiolabs
CVE-2026-45065
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedSymfony 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, UrlGenerator validates route parameters against a pattern built as ^ plus the raw requirement plus $; with ungrouped alternations, middle alternatives match as unanchored substrings, allowing a value such as //evil.com to satisfy a common locale requirement and generate a protocol-relative off-site URL. This issue is fixed in versions 5.4.52, 6.4.40, 7.4.12, and 8.0.12.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceSymfony's UrlGenerator validates route parameters against a regex pattern built as ^ plus the raw requirement plus $; with ungrouped alternations, middle alternatives match as unanchored substrings, allowing values like //evil.com to bypass common locale requirements and generate protocol-relative off-site URLs, creating an open redirect vulnerability.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
SymfonyFramework / library
< 5.4.52>= 6.0.0, < 6.4.40>= 7.0.0, < 7.4.12>= 8.0.0, < 8.0.12CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Symfony versionRun `composer show sensiolabs/symfony-pack` or inspect the `vendor/sensiolabs/symfony-pack/composer.json` file to find the installed Symfony version. Alternatively, check your project's `composer.lock` for the `symfony/symfony` package version.Affected if The installed version is less than 5.4.52, or between 6.0.0 and 6.4.39, or between 7.0.0 and 7.4.11, or between 8.0.0 and 8.0.11
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Locate route configuration filesFind YAML, XML, or PHP route definition files in your `config/routes/` directory or annotations in your controller files. Look for routes that define requirements on parameters using the 'requirements' key.Affected if Routes define regex requirements on URL parameters, particularly those using alternation patterns (e.g., `requirements: { _locale: en|fr|de }`)
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Identify routes with locale or host requirementsSearch route configurations for requirements that include alternations, especially `_locale`, `_host`, or custom path parameters. Look for patterns like `en|fr` or domain patterns with multiple alternatives.Affected if Routes contain parameter requirements with ungrouped alternations that could be bypassed by protocol-relative URLs like `//evil.com`
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Test URL generation for open redirectIf using the Symfony router programmatically, generate a URL with a parameter value of `//evil.com` against a route that has locale requirements (e.g., expecting `en` or `fr`). Example: `$router->generate('route_name', ['_locale' => '//evil.com'])`. Inspect the resulting URL to see if it produces an off-site redirect.Affected if The generated URL contains the bypass value and produces a protocol-relative URL pointing to an external domain
You are affected if your Symfony version falls within the vulnerable ranges AND your application uses route parameter requirements with alternations that can be bypassed by protocol-relative URLs like //evil.com
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped5.4.526.4.407.4.12
Update Symfony to version 5.4.52, 6.4.40, 7.4.12, or 8.0.12 or later to patch the regex validation flaw in UrlGenerator.
Upgrade to 5.4.52, 6.4.40, 7.4.12, or 8.0.12 depending on your major version branch
- 1. Determine the current Symfony version by checking your composer.json or running `composer show symfony/symfony | grep version`
- 2. Identify which major version branch you are on (5.x, 6.x, 7.x, or 8.x)
- 3. Run `composer require symfony/symfony:^5.4.52` for 5.x, `composer require symfony/symfony:^6.4.40` for 6.x, `composer require symfony/symfony:^7.4.12` for 7.x, or `composer require symfony/symfony:^8.0.12` for 8.x
- 4. Run `composer update symfony/symfony` to apply the upgrade
- 5. Clear Symfony's cache with `php bin/console cache:clear`
- 6. Test application functionality to verify the upgrade does not break existing features
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Symfony
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-45065 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-45065 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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