# CVE-2026-55378: JS Recon: Command injection in PR Branch Checker workflow via untrusted pull request context values

> Remote attackers can execute arbitrary commands on GitHub Actions runners via shell metacharacters in pull request branch or fork names.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Aug 2026
- **Updated:** 1 Sep 2026
- **Also known as:** GHSA-w9cj-mg3x-qjm4

## What is CVE-2026-55378?

CVE-2026-55378 is a critical command injection vulnerability in shriyanss js-recon, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

JS Recon is a JavaScript enumeration and SAST tool. From 1.2.1-beta.1 until 1.3.1-beta.2, the PR Branch Checker workflow in .github/workflows/pr_checker.yml places github.head_ref and github.event.pull_request.head.repo.full_name into BRANCH_NAME and SOURCE_REPO and interpolates those untrusted values into a shell gh pr comment command. A remote user who opens a pull request can use shell metacharacters in a branch or fork name to execute commands in the GitHub Actions runner with the workflow's GITHUB_TOKEN, which has pull-requests write permission. This issue is fixed in version 1.3.1-beta.2.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2026-55378?


## How do I fix CVE-2026-55378?

No fix has been published for CVE-2026-55378 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-55378 being exploited?

There is no known exploitation of CVE-2026-55378 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55378 and fix it if it is affected.

What it is: CVE-2026-55378 is a critical command injection vulnerability in shriyanss js-recon, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-55378 in the wild and no public exploit code.

Affected product: shriyanss js-recon. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-55378/ (Markdown: https://insights.sbomify.com/CVE-2026-55378/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55378
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55378
- OSV: https://osv.dev/vulnerability/CVE-2026-55378

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55378/
Summaries are generated and may contain mistakes; the official description above is the record.