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Unratedamended

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in ZMarkdown

GHSA-2c83-wfv3-q25f

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (rebber 5.2.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm rebber

    Affected
    < 5.2.1
    Fixed in
    5.2.1

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

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: For more information If you have any questions or comments about this…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-2c83-wfv3-q25f

  2. Revision 1 · created ·

    Published from osv record GHSA-2c83-wfv3-q25f

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-2c83-wfv3-q25f

Advisory: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in ZMarkdown
IDs: GHSA-2c83-wfv3-q25f
Record: https://patchnext.com/advisories/ghsa-2c83-wfv3-q25f (revision 2, source checked 26 Oct 2026, 12:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: rebber 5.2.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm rebber: affected < 5.2.1; fixed in 5.2.1

## Suggested inspection (read-only)
- `npm ls rebber --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on rebber.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-2c83-wfv3-q25f (OSV record GHSA-2c83-wfv3-q25f lists affected ranges: npm rebber >=0 <5.2.1 (fixed))
- Verified: https://github.com/advisories/GHSA-2c83-wfv3-q25f (GitHub-reviewed advisory GHSA-2c83-wfv3-q25f lists affected ranges: npm rebber >=0 <5.2.1)

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