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.

Multiple Vulnerabilities in Symfony

The version of Symfony and/or the Symfony HTML Sanitizer Component installed on the remote host is prior to 6.1.x prior to 6.4.40, 7.0.x prior to 7.4.12, 8.0.x prior to 8.0.12. and, therefore, affected by multiple vulnerabilities:

  - A visual spoofing vulnerability exists in Symfony Component HtmlSanitizer's UrlSanitizer due to failure to     strip Unicode BiDi (bidirectional) formatting characters from URLs. An unauthenticated, remote attacker can     exploit this, via crafted URLs containing directional override characters in sanitized content, to display     misleading link text that visually differs from the actual destination, enabling phishing attacks against     users who view the sanitized HTML. (CVE-2026-45064)

  - An allowlist bypass vulnerability exists in Symfony Component HtmlSanitizer's allowLinkHosts/allowLinkSchemes     and allowMediaHosts/allowMediaSchemes configuration methods due to parsing discrepancies between RFC-3986     (server-side) and WHATWG URL Standard (browser-side), and incorrect element type checking for  tags. An     unauthenticated, remote attacker can exploit this, via crafted URLs using backslash/slash normalization     differences or misclassified elements, to bypass host and scheme allowlists and inject malicious     off-allowlist URLs into sanitized content. (CVE-2026-45066)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number. Also note that this plugin does not distinguish between PHP packages installed via the OS package manager, PHP packages installed via Composer, or other sources. As a result, packages provided by your OS package repository may have backported fixes that this plugin may incorrectly report as vulnerable. Please refer to the OS-specific plugins for CVE-2026-45064 and CVE-2026-45066 to check for backported fixes.

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6312 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6312-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     May 31, 2026                          https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : symfony     CVE ID         : CVE-2024-50340 CVE-2026-45063 CVE-2026-45064 CVE-2026-45065                      CVE-2026-45066 CVE-2026-45067 CVE-2026-45068 CVE-2026-45069                      CVE-2026-45071 CVE-2026-45072 CVE-2026-45073 CVE-2026-45077                      CVE-2026-45133 CVE-2026-45304 CVE-2026-45305 CVE-2026-45754                      CVE-2026-46626 CVE-2026-48489 CVE-2026-48736 CVE-2026-48760                      CVE-2026-48761 CVE-2026-48784

    Multiple vulnerabilities have been found in the Symfony PHP framework     which could lead to a bypass of security controls, cross-site scripting,     denial of service, SQL injection, email header injection, information     disclosure or code execution via PHP object deserialization.

    For the stable distribution (trixie), these problems have been fixed in     version 6.4.41+dfsg-0+deb13u1.

    We recommend that you upgrade your symfony packages.

    For the detailed security status of symfony please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/symfony

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2026-45066)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-45066)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
318792	Symfony and Symfony HTML Sanitizer Component 6.1.x < 6.4.40 / 7.0.x < 7.4.12 / 8.0.x 8.0.12 Multiple Vulnerabilities	Nessus	Misc.	medium
318121	Debian dsa-6312 : php-symfony - security update	Nessus	Debian Local Security Checks	critical
442401	SCA: security update for symfony/html-sanitizer, symfony/symfony (GHSA-qc95-4862-92fh)	Tenable Cloud Security	SCA Checks	low
442401	SCA: security update for symfony/html-sanitizer, symfony/symfony (GHSA-qc95-4862-92fh)	Tenable Self-Hosted Container Security	SCA Checks	low
316433	Linux Distros Unpatched Vulnerability : CVE-2026-45066	Nessus	Misc.	low

Detections

Analytics

CVE-2026-45066

low

Tenable Plugins

Coming Soon

medium

critical

low

low

low