# CVE-2026-4851: GRID::Machine versions through 0.127 for Perl allows arbitrary code execution via unsafe deserialization

> A malicious remote host can execute arbitrary code on the client via unsafe deserialization in the GRID::Machine Perl RPC library.

- **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:** 29 Mar 2026
- **Updated:** 1 Apr 2026
- **Also known as:** GHSA-p6f4-6qxg-8xqv

## What is CVE-2026-4851?

CVE-2026-4851 is a critical unsafe deserialization vulnerability in CASIANO GRID::Machine, published on 29 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

GRID::Machine versions through 0.127 for Perl allows arbitrary code execution via unsafe deserialization.

GRID::Machine provides Remote Procedure Calls (RPC) over SSH for Perl. The client connects to remote hosts to execute code on them. A compromised or malicious remote host can execute arbitrary code back on the client through unsafe deserialization in the RPC protocol.

read_operation() in lib/GRID/Machine/Message.pm deserialises values from the remote side using eval()

  $arg .= '$VAR1';
  my $val = eval "no strict; $arg"; # line 40-41

$arg is raw bytes from the protocol pipe. A compromised remote host can embed arbitrary perl in the Dumper-formatted response:

  $VAR1 = do { system("..."); };

This executes on the client silently on every RPC call, as the return values remain correct.

This functionality is by design but the trust requirement for the remote host is not documented in the distribution.

Weakness: CWE-95 (Improper Neutralization of Directives in Dynamically Evaluated Code), CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-4851?

It affects 1 product.


Products: Casiano Grid\.

## How do I fix CVE-2026-4851?

No fix has been published for CVE-2026-4851 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4851 being exploited?

There is no known exploitation of CVE-2026-4851 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4851 and fix it if it is affected.

What it is: CVE-2026-4851 is a critical unsafe deserialization vulnerability in CASIANO GRID::Machine, published on 29 Mar 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-2026-4851 in the wild and no public exploit code.

Affected product: CASIANO GRID::Machine. 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-2026-4851/ (Markdown: https://insights.sbomify.com/CVE-2026-4851/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4851
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4851
- OSV: https://osv.dev/vulnerability/CVE-2026-4851

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-4851/
Summaries are generated and may contain mistakes; the official description above is the record.