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Fencer Intel
critical 9.8

CVE-2026-4851 json

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

published 7mo ago modified 4mo ago also EUVD-2026-16957

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

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.

Is CVE-2026-4851 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
7mo ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • CASIANO GRID::Machine

Classification

Weakness
  • CWE-502 Deserialization of Untrusted Data
  • CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.