githubtoplanguages generates a user's top GitHub languages as an SVG. The .github/workflows/discord-issue.yml workflow runs when an issue is opened or closed and interpolates github.event.issue.title directly into the Bash assignment for ISSUE_TITLE before shell parsing. An issue title containing shell command-substitution syntax can therefore execute commands on the GitHub Actions runner before the title is included in the Discord notification sent through DISCORD_WEBHOOK. Successful exploitation can manipulate or spoof trusted bot notifications and may expose the Discord webhook secret or other workflow environment data, depending on repository permissions. This issue is fixed by commit 6bf9c3a9cb66c937b9047ca266b3d02f2bb11027.

Affected: GitHub Actions: gouef/githubtoplanguages

### Summary

A GitHub Actions workflow is vulnerable to command injection through the issue title.

The workflow is triggered when an issue is opened or closed, and it directly inserts `github.event.issue.title` into a Bash variable assignment. If an issue title contains command substitution syntax, Bash evaluates it during the workflow run.

### Details

The vulnerable workflow is:

`.github/workflows/discord-issue.yml`

The issue title is directly interpolated into a Bash script:

```bash ISSUE_TITLE="${{ github.event.issue.title || github.event.pull_request.title }}" ```

Because GitHub Actions expressions are expanded before Bash executes the script, an attacker-controlled issue title containing command substitution syntax can be evaluated by the shell.

In the original workflow, the resulting value is then included in a Discord notification payload:

```bash curl -H "Content-Type: application/json" \ -X POST \ -d "{\"username\": \"GitHub Bot\", \"content\": \"${STATUS} created by **${AUTHOR}**: **${ISSUE_TITLE}**\n🔗 ${ISSUE_URL}\"}" \ "$DISCORD_WEBHOOK" ```

### PoC

For safety, I reproduced this only in my fork. I did not trigger the original repository’s Discord webhook.

I kept the vulnerable Bash assignment unchanged and replaced the Discord webhook request with `echo` statements to observe the result safely.

Test issue title:

```text title: $(whoami) ```

Observed workflow log:

```text ISSUE_TITLE=title: runner ```

This confirms that `$(whoami)` was exec…