CVE-2021-43809Public exploit

Local code execution via Git option injection

Published Dec 8, 2021 · Updated Nov 3, 2025

Argument injection in RubyGems Bundler before 2.2.33 allows local users to execute arbitrary code via a crafted Git URL in a Gemfile. Bundler passes a dash-leading Git URL from the Gemfile to git clone without an option terminator, so Git interprets it as the upload-pack option. Execution requires a victim to open the attacker-supplied directory and run a Bundler command that evaluates the Gemfile.

CVSS severity6.7
Medium
EPSS probability2.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Argument injection in RubyGems Bundler before 2.2.33 allows local users to execute arbitrary code via a crafted Git URL in a Gemfile. Bundler passes a dash-leading Git URL from the Gemfile to git clone without an option terminator, so Git interprets it as the upload-pack option. Execution requires a victim to open the attacker-supplied directory and run a Bundler command that evaluates the Gemfile.

The record

CVE
CVE-2021-43809
Published
Dec 8, 2021
Updated
Nov 3, 2025
Vendor
libwww-perl
Product
RubyGems
Classifications
CWE-88, T1204.002
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record 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=< 2.2.33

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

libwww-perl · RubyGemsversion=< 2.2.33

Published CVSS scores

9.3NIST NVDAV:N/AC:M/Au:N/C:C/I:C/A:C
7.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
6.7GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-88Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
T1204.002User Execution: Malicious File

Public exploit references

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Technologies

Your stack

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Your stack

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