Ecosyste.ms: Advisories

Security Advisories: GSA_kwCzR0hTQS1mM3FyLXFyNHgtajI3M84AA5bM

php-svg-lib lacks path validation on font through SVG inline styles

Summary

php-svg-lib fails to validate that font-family doesn't contain a PHAR url, which might leads to RCE on PHP < 8.0, and doesn't validate if external references are allowed. This might leads to bypass of restrictions or RCE on projects that are using it, if they do not strictly revalidate the fontName that is passed by php-svg-lib.

Details

The Style::fromAttributes(), or the Style::parseCssStyle() should check the content of the font-family and prevents it to use a PHAR url, to avoid passing an invalid and dangerous fontName value to other libraries. The same check as done in the Style::fromStyleSheets might be reused :

                if (
                    \array_key_exists("font-family", $styles)
                    && (
                        \strtolower(\substr($this->href, 0, 7)) === "phar://"
                        || ($this->document->allowExternalReferences === false && \strtolower(\substr($this->href, 0, 5)) !== "data:")
                    )
                ) {
                    unset($style["font-family"]);
                }

PoC

Parsing the following SVG :

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns:svg="http://www.w3.org/2000/svg" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="200" height="200">
    <text x="20" y="35" style="color:red;font-family:phar:///path/to/whatever.phar/blaklis;">My</text>
</svg>

will pass the phar:///path/to/whatever.phar/blaklis as $family in SurfaceCpdf::setFont, which is then passed to the canvas selectFont as a $fontName.

Impact

Libraries using this library as a dependency might be vulnerable to some bypass of restrictions, or even RCE, if they do not double check the value of the fontName that is passed by php-svg-lib

Permalink: https://github.com/advisories/GHSA-f3qr-qr4x-j273
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS1mM3FyLXFyNHgtajI3M84AA5bM
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: 2 months ago
Updated: 2 months ago

CVSS Score: 6.8
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L

Identifiers: GHSA-f3qr-qr4x-j273, CVE-2024-25117
References:

• https://github.com/dompdf/php-svg-lib/security/advisories/GHSA-f3qr-qr4x-j273
• https://github.com/dompdf/php-svg-lib/commit/732faa9fb4309221e2bd9b2fda5de44f947133aa
• https://github.com/dompdf/php-svg-lib/commit/8ffcc41bbde39f09f94b9760768086f12bbdce42
• https://nvd.nist.gov/vuln/detail/CVE-2024-25117
• https://github.com/advisories/GHSA-f3qr-qr4x-j273

Repository: https://github.com/dompdf/php-svg-lib
Blast Radius: 29.4

Affected Packages