CVE-2026-4496Public exploit

Local command execution via shell-interpreted Git arguments

Published Mar 20, 2026 · Updated Mar 20, 2026

OS command injection in sigmade Simple Merge Review MCP 1.0.0 allows local users to execute arbitrary commands through MCP tool inputs. GitUtils.executeGit passes command strings containing branch and filename values to execSync, allowing shell metacharacters to alter the invoked command. A caller able to submit show_merge_diff, quick_merge_summary, or show_file_diff requests can execute commands with the server process's privileges.

CVSS severity5.3
Medium
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in sigmade Simple Merge Review MCP 1.0.0 allows local users to execute arbitrary commands through MCP tool inputs. GitUtils.executeGit passes command strings containing branch and filename values to execSync, allowing shell metacharacters to alter the invoked command. A caller able to submit show_merge_diff, quick_merge_summary, or show_file_diff requests can execute commands with the server process's privileges.

The record

CVE
CVE-2026-4496
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
sigmade
Product
Simple Merge Review MCP
Classifications
CWE-77, CWE-78, T1059
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=785aa159f262a02d5791a5d8a8e13c507ac42880

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

sigmade · Simple Merge Review MCPversion=785aa159f262a02d5791a5d8a8e13c507ac42880

Published CVSS scores

4.3VulDBAV:L/AC:L/Au:S/C:P/I:P/A:P
1.9NVDCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
5.3VulDBCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059Command and Scripting Interpreter

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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