CVE-2026-49260

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.

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.

Summary

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 (Snappy 1.7.1).

Affected versions

pontedilana/php-weasyprint versions <= 2.5.0 (current master tip commit c2b51fed0bf442c3bf0292b879a09944d436f2a0, 2026-04-03).

Patched in: 2.5.1

Privilege required

Any caller that can influence the binary string handed to the Pdf constructor or to AbstractGenerator::setBinary(). Typical reach paths:

• An application config file (config/services.yaml, .env, helm chart value) read at boot time, where the path is auto-detected from environment or driven by a per-tenant override.
• An admin UI that lets operators pick between multiple WeasyPrint builds (weasyprint-v60, weasyprint-v66) for compatibility reasons.
• A multi-tenant SaaS that resolves binary location from a tenant config row.

Once an attacker plants a string containing shell metacharacters in one of those channels, every subsequent generate() call shells out the injected payload as the PHP process user.

Vulnerable code

src/AbstractGenerator.php#L169-L172:

protected function buildCommand(string $binary, string $input, string $output, array $options = []): string
{
    $escapedBinary = \escapeshellarg($binary);
    $command = \is_executable($escapedBinary) ? $escapedBinary : $binary;

src/Pdf.php#L167-L170 overrides buildCommand with the same guard:

protected function buildCommand(string $binary, string $input, string $output, array $options = []): string
{
    $escapedBinary = \escapeshellarg($binary);
    $command = \is_executable($escapedBinary) ? $escapedBinary : $binary;

escapeshellarg($binary) returns a single-quoted string. is_executable() then looks up a file whose name literally contains the surrounding single-quote characters, which essentially never exists. The ternary therefore always falls through to the right-hand side, where $command is the raw, unescaped $binary string. The rest of the command construction (options, input, output) is correctly escaped, so injection has to land in the binary segment — which is exactly the segment configuration-driven deployments treat as trusted.

This is the same primitive KnpLabs/snappy patched in version 1.7.1. The README of php-weasyprint states: "This library is massively inspired by KnpLabs/snappy, of which it aims to be a one-to-one substitute (GeneratorInterface is the same)." The vulnerable buildCommand was copied verbatim and never updated.

How $binary reaches the shell

caller code
  └── new Pdf($binary)                 // src/Pdf.php constructor
        └── parent::__construct($binary)
              └── $this->setBinary($binary)               // src/AbstractGenerator.php:276
                        $this->binary =…

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.

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.

Summary

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 (Snappy 1.7.1).

Affected versions

pontedilana/php-weasyprint versions <= 2.5.0 (current master tip commit c2b51fed0bf442c3bf0292b879a09944d436f2a0, 2026-04-03).

Patched in: 2.5.1

Privilege required

Any caller that can influence the binary string handed to the Pdf constructor or to AbstractGenerator::setBinary(). Typical reach paths:

• An application config file (config/services.yaml, .env, helm chart value) read at boot time, where the path is auto-detected from environment or driven by a per-tenant override.
• An admin UI that lets operators pick between multiple WeasyPrint builds (weasyprint-v60, weasyprint-v66) for compatibility reasons.
• A multi-tenant SaaS that resolves binary location from a tenant config row.

Once an attacker plants a string containing shell metacharacters in one of those channels, every subsequent generate() call shells out the injected payload as the PHP process user.

Vulnerable code

src/AbstractGenerator.php#L169-L172:

protected function buildCommand(string $binary, string $input, string $output, array $options = []): string
{
    $escapedBinary = \escapeshellarg($binary);
    $command = \is_executable($escapedBinary) ? $escapedBinary : $binary;

src/Pdf.php#L167-L170 overrides buildCommand with the same guard:

protected function buildCommand(string $binary, string $input, string $output, array $options = []): string
{
    $escapedBinary = \escapeshellarg($binary);
    $command = \is_executable($escapedBinary) ? $escapedBinary : $binary;

escapeshellarg($binary) returns a single-quoted string. is_executable() then looks up a file whose name literally contains the surrounding single-quote characters, which essentially never exists. The ternary therefore always falls through to the right-hand side, where $command is the raw, unescaped $binary string. The rest of the command construction (options, input, output) is correctly escaped, so injection has to land in the binary segment — which is exactly the segment configuration-driven deployments treat as trusted.

This is the same primitive KnpLabs/snappy patched in version 1.7.1. The README of php-weasyprint states: "This library is massively inspired by KnpLabs/snappy, of which it aims to be a one-to-one substitute (GeneratorInterface is the same)." The vulnerable buildCommand was copied verbatim and never updated.

How $binary reaches the shell

caller code
  └── new Pdf($binary)                 // src/Pdf.php constructor
        └── parent::__construct($binary)
              └── $this->setBinary($binary)               // src/AbstractGenerator.php:276
                        $this->binary =…