Github · Github Actions · CVE-2026-34243
**Name of the Vulnerable Software and Affected Versions**
njzjz/wenxian (affected versions not specified)
**Description**
A command injection flaw exists in a GitHub Actions workflow due to the direct use of untrusted user input from `issue comment.body` within a shell command. The workflow is triggered by `issue comment`, which is controllable by external users. The vulnerable step interpolates the value of `github.event.comment.body` directly into a shell command without sanitization, creating a command injection risk. Specifically, the following command is vulnerable: `echo identifiers=$(echo "${{ github.event.comment.body }}" | grep -oE '@njzjz-bot .*' | head -n1 | cut -c12- | xargs) >> $GITHUB OUTPUT`. The extracted value is also reused in another step, potentially propagating unsafe content. A proof of concept demonstrates that an attacker can inject arbitrary shell commands via issue comments, such as using the payload `@njzjz-bot paper123" ) ; whoami ; #`. Successful injection allows for the execution of arbitrary commands in the GitHub Actions runner, potentially leading to access to the `GITHUB TOKEN`, exfiltration of repository data, and compromise of the CI/CD pipeline.
**Recommendations**
Avoid directly interpolating untrusted user input into shell commands. Instead, pass `github.event.comment.body` through an environment variable and reference it safely within the script.