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

published 2026-06-19 4 mo ago modified 2026-10-25 14 d ago also GHSA-2fmj-p74r-3wjm , EUVD-2026-38053

cvss: 8.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.7%; EPSS 0.7% chance of exploitation in 30 days, percentile 54%
public exploits: 0; none known

PhpWeasyPrint is a PHP library allowing PDF generation from a URL or an HTML page. Prior to version 2.6.0, `pontedilana/php-weasyprint` guarded the output filename against the `phar://` stream wrapper with a case-sensitive blacklist. PHP stream wrappers are case-insensitive, so `PHAR://`, `Phar://`, etc. bypass the check and reach `fileExists()` (`file_exists()`) in `prepareOutput()`. On PHP 7 (which the library still supports — PHP 7.4+), this triggers deserialization of a crafted PHAR archive's metadata, leading to remote code execution. This is the patch-bypass of CVE-2023-28115. The same issue and fix were handled upstream in KnpLabs/snappy (GHSA-92rv-4j2h-8mjj). PhpWeasyPrint version 2.6.0 contains a patch for the issue.

Patch / fix

fixed in 1 links 2

packagist pontedilana/php-weasyprint 2.6.0

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 4 mo ago (2026-06-22)

Exploit prediction

0.73% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/pontedilana/php-weasyprint/security/advisories/GHSA-2fmj-p74r-3wjm referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub	3.1	8.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
packagist	pontedilana/php-weasyprint	<2.6.0	2.6.0

Affected products

pontedilana php-weasyprint

Classification

Weakness

CWE-502 Deserialization of Untrusted Data

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary