# CVE-2026-34243: wenxian: Command Injection in GitHub Actions Workflow via `issue_comment.body`

> Attackers can execute arbitrary code on CI runners by injecting commands into issue comments processed by the wenxian tool.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 31 Mar 2026
- **Updated:** 2 Apr 2026
- **Also known as:** GHSA-r4fj-r33x-8v88

## What is CVE-2026-34243?

CVE-2026-34243 is a critical command injection vulnerability in njzjz wenxian, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

wenxian is a tool to generate BIBTEX files from given identifiers (DOI, PMID, arXiv ID, or paper title). In versions 0.3.1 and prior, a GitHub Actions workflow uses untrusted user input from issue_comment.body directly inside a shell command, allowing potential command injection and arbitrary code execution on the runner. At time of publication, there are no publicly available patches.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-77 (Improper Neutralization of Special Elements used in a Command)

## Which versions are affected by CVE-2026-34243?

1 open source package ship an affected version, including njzjz/wenxian. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `njzjz/wenxian` | GitHub Actions | All versions to 0.3.1 | None |

Products: Njzjz Wenxian.

## How do I fix CVE-2026-34243?

No fix has been published for CVE-2026-34243 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34243 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34243 exists.

Public exploit code:

- Research lab reproduction of CVE-2026-34243 (GHSA-r4fj-r33x-8v88): command injection via issue_comment.body in .github/workflows/comment.yaml — snapshot of njzjz/wenxian@ca4e04de86aa970c0e3cb1c7f2bd103d339fbe51 (github_poc): https://github.com/pvharmo2/gha-lab-85f022290a

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34243 and fix it if it is affected.

What it is: CVE-2026-34243 is a critical command injection vulnerability in njzjz wenxian, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34243 exists.

Affected packages and fixed versions:
- njzjz/wenxian (GitHub Actions): affected all versions up to 0.3.1; no fix listed

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-2026-34243/ (Markdown: https://insights.sbomify.com/CVE-2026-34243/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34243
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34243
- OSV: https://osv.dev/vulnerability/CVE-2026-34243

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34243/
Summaries are generated and may contain mistakes; the official description above is the record.