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Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in ZMarkdownGHSA-2c83-wfv3-q25f

GHSA-2c83-wfv3-q25f is a security vulnerability in rebber. A fix is available for rebber — see the affected versions and patch details below.

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 7, 2021 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

2other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
rebbernpm
181downloads / week

Description

Impact

A Remote Command Execution vulnerability was found in the rebber module, which allowed execution of arbitrary commands. The reported problem came from CodeBlocks, which could be escaped to insert malicious LaTeX.

Anyone using rebber without sanitation of code content or a custom macro is impacted by this vulnerability. Here is an example of a Markdown content that will exploit the vulnerability:

```
\end{CodeBlock}

\immediate\write18{COMMAND > outputrce}
\input{outputrce}

\begin{CodeBlock}{text}
```

Will insert into the generated LaTeX the result of executing COMMAND on the system.

Patches

The vulnerability has been patched in version 5.2.1. If impacted, you should update to this version as soon as possible.

Workarounds

It is possible to mitigate the vulnerability without upgrading by using a custom code macro. Please make sure this custom macro escapes your closing LaTeX sequence. For the example above, use:

const escaped = content.replace(new RegExp('\\\\end\\s*{CodeBlock}', 'g'), '')

For more information

If you have any questions or comments about this advisory, open an issue in ZMarkdown.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmrebberall versions5.2.1npm install rebber@5.2.1

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rebber, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update rebber to 5.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2c83-wfv3-q25f is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact A Remote Command Execution vulnerability was found in the rebber module, which allowed execution of arbitrary commands. The reported problem came from CodeBlocks, which could be escaped to insert malicious LaTeX. Anyone using `rebber` without sanitation of code content or a custom macro is impacted by this vulnerability. Here is an example of a Markdown content that will exploit the vulnerability: ````markdown ``` \end{CodeBlock} \immediate\write18{COMMAND > outputrce} \input{outputrce} \begin{CodeBlock}{text} ``` ```` Will insert into the generated LaTeX the result of executi
O3 Security · Impact-Aware SCA

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