PhpWeasyPrint: shell command injection via configurable WeasyPrint binary path due to inverted is_executable() guard (mirror of KnpLabs/snappy GHSA-vpr4-p6fq-85jc)

published 2026-06-19 4 mo ago modified 2026-10-25 14 d ago also GHSA-f5gc-qxf8-mh9g , EUVD-2026-38048

cvss: 8.2; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits: 0; none known

PhpWeasyPrint is a PHP library allowing PDF generation from a URL or an HTML page. Prior to version 2.5.1, `pontedilana/php-weasyprint` builds the shell command for WeasyPrint by passing the binary path through `escapeshellarg()` first and then checking the *quoted* result with `is_executable()`. On POSIX `escapeshellarg('/usr/local/bin/weasyprint')` returns `'/usr/local/bin/weasyprint'` with the single-quote characters as part of the string, so `is_executable()` looks for a file whose actual name includes those quotes. That file never exists, the "safe" branch is dead code, and the raw `$binary` string (set via the constructor or `setBinary()`) flows directly into `Symfony\Component\Process\Process::fromShellCommandline()`. Any deployment whose binary path is sourced from configuration, an environment variable, or a per-tenant setting reaches a shell-command-injection sink. The library is documented as a one-to-one substitute for KnpLabs/snappy and inherited the exact pre-fix codepath KnpLabs patched in GHSA-vpr4-p6fq-85jc. PhpWeasyPrint version 2.5.1 contains a patch for the issue.

Patch / fix

fixed in 1 links 2

packagist pontedilana/php-weasyprint 2.5.1

CISA SSVC

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

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/pontedilana/php-weasyprint/security/advisories/GHSA-f5gc-qxf8-mh9g referenced PoC, tagged "exploit" by a source, unverified
github.com https://github.com/KnpLabs/snappy/security/advisories/GHSA-vpr4-p6fq-85jc referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.2	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
GitHub	3.1	8.2	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
packagist	pontedilana/php-weasyprint	<2.5.1	2.5.1

Affected products

pontedilana php-weasyprint

Classification

Weakness

CWE-78 Improper Neutralization of Special Elements used in an OS Command

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