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SymfonyFramework / library · Sensiolabs

CVE-2026-45066

MEDIUM · 6.1 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 6.4.40 / 7.4.12 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges 5 weeks old

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 · unedited
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.1.0-BETA1 until 6.4.40, 7.4.12, and 8.0.12, HtmlSanitizer URL sanitization can allow off-allowlist URLs through allowLinkHosts() or allowMediaHosts() because UrlSanitizer::parse() follows RFC 3986 while browsers follow WHATWG URL parsing, and because <area href> is checked against the media policy rather than the link policy. This issue is fixed in versions 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 confidence

The HtmlSanitizer component in Symfony has a URL parsing discrepancy where UrlSanitizer::parse() follows RFC 3986 while browsers use WHATWG URL parsing, and <area href> tags are incorrectly validated against the media policy instead of the link policy. This allows specially crafted URLs to bypass allowLinkHosts() and allowMediaHosts() allowlists, potentially enabling XSS or other attacks through unsanitized URLs.

MitigationUpgrade Symfony to version 6.4.40, 7.4.12, or 8.0.12 to apply the patch, and verify that the HTML sanitization continues to function correctly after the update.

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
Affected:>= 6.1.0, < 6.4.40>= 7.0.0, < 7.4.12>= 8.0.0, < 8.0.12

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Symfony version
    Run 'composer show symfony/framework-bundle' or check your composer.lock file for the installed Symfony version
    Affected if The installed version is >= 6.1.0 and < 6.4.40, OR >= 7.0.0 and < 7.4.12, OR >= 8.0.0 and < 8.0.12
  2. Confirm HtmlSanitizer usage
    Search your codebase for usage of 'HtmlSanitizer' or 'HtmlSanitizerInterface' - look for sanitization of HTML that may contain <area> tags with href attributes
    Affected if Your application uses the HtmlSanitizer component to clean user-provided HTML
  3. Check for link or media host allowlists
    Search your sanitizer configuration for 'allowLinkHosts' or 'allowMediaHosts' method calls that define permitted domains
    Affected if allowLinkHosts() or allowMediaHosts() are configured with specific allowed domains (the bypass affects these allowlists)
  4. Inspect <area href> processing
    Review any HTML input that may contain <area href="..."> tags being passed through the sanitizer, particularly if those URLs reference external domains
    Affected if Your application sanitizes HTML containing <area> elements with href attributes pointing to external URLs

You are affected if your Symfony version falls within the vulnerable ranges AND you use HtmlSanitizer with allowLinkHosts/allowMediaHosts configuration while processing HTML that contains <area href> tags from untrusted sources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 6.4.40 / 7.4.12 / 8.0.12 or later
Fixed in 6.4.407.4.128.0.12
Interim mitigation

Upgrade Symfony to version 6.4.40, 7.4.12, or 8.0.12 to apply the patch, and verify that the HTML sanitization continues to function correctly after the update.

Recommended fix High confidence

Symfony 6.4.40, 7.4.12, or 8.0.12 depending on your major version branch

  1. Identify your current Symfony version branch (6.x, 7.x, or 8.x) by checking your composer.json or lock file
  2. For Symfony 6.x: Update composer.json to require "symfony/http-kernel": "6.4.*" or run `composer require symfony/http-kernel:6.4.40 --update-with-all-dependencies`
  3. For Symfony 7.x: Update composer.json to require "symfony/http-kernel": "7.4.*" or run `composer require symfony/http-kernel:7.4.12 --update-with-all-dependencies`
  4. For Symfony 8.x: Update composer.json to require "symfony/http-kernel": "8.0.*" or run `composer require symfony/http-kernel:8.0.12 --update-with-all-dependencies`
  5. Run `composer update` to install the fixed version
  6. Run your test suite to verify the HtmlSanitizer functionality works as expected after the upgrade
Caveat Minor version upgrades within the same major typically have minimal breaking changes, but review the Symfony changelog for any deprecation warnings relevant to your application

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Symfony Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-45066 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data