CVE-2026-17431 Vulnerability Analysis & Exploit Details

CVE-2026-17431 Vulnerability Summary

CVE-2026-17431: PDF::WebKit versions through 1.2 for Perl allow OS command injection via a 2-arg open() of the output path in to_pdf and of stylesheet paths in _style_tag_for. to_pdf reads the generated PDF back from its path argument, and _style_tag_for reads each entry of the stylesheets list, by assigning the path to a local @ARGV and reading it with the diamond operator, which opens each @ARGV element with Perl's 2-arg open(). A value that begins or ends with a pipe ("| cmd", "cmd |") is run as a command rather than opened as a file, and one that begins with a redirect ("> path", ">> path") opens that path for write or append. to_file forwards its path argument to to_pdf and reaches the same read. Any caller that forwards untrusted input as the output path or as a stylesheets entry can run a command under the process UID; with the "cmd |" form the command's output is returned in place of the PDF, and with the "> path" form the named file is truncated. Stylesheets may only be added to an HTML source, so a URL or file source exposes the output path alone.

CVE-2026-17431 References

External References

• https://github.com/kingpong/perl-PDF-WebKit/issues/8
• https://security.metacpan.org/patches/P/PDF-WebKit/1.2/CVE-2026-17431-r1.patch
• https://wkhtmltopdf.org/status.html

CWE Common Weakness Enumeration

CAPEC Common Attack Pattern Enumeration and Classification

• Command Line Execution through SQL Injection CAPEC-108 An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
• Command Delimiters CAPEC-15 An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or denylist input validation, as opposed to allowlist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or denylist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.
• Exploiting Multiple Input Interpretation Layers CAPEC-43 An attacker supplies the target software with input data that contains sequences of special characters designed to bypass input validation logic. This exploit relies on the target making multiples passes over the input data and processing a "layer" of special characters with each pass. In this manner, the attacker can disguise input that would otherwise be rejected as invalid by concealing it with layers of special/escape characters that are stripped off by subsequent processing steps. The goal is to first discover cases where the input validation layer executes before one or more parsing layers. That is, user input may go through the following logic in an application: <parser1> --> <input validator> --> <parser2>. In such cases, the attacker will need to provide input that will pass through the input validator, but after passing through parser2, will be converted into something that the input validator was supposed to stop.
• Argument Injection CAPEC-6 An attacker changes the behavior or state of a targeted application through injecting data or command syntax through the targets use of non-validated and non-filtered arguments of exposed services or methods.
• OS Command Injection CAPEC-88 In this type of an attack, an adversary injects operating system commands into existing application functions. An application that uses untrusted input to build command strings is vulnerable. An adversary can leverage OS command injection in an application to elevate privileges, execute arbitrary commands and compromise the underlying operating system.

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