CVE-2021-3934

Arbitrary command execution via unsafe URL decoding

Published Nov 12, 2021 · Updated Aug 3, 2024

OS command injection in Oh My Zsh before commit 6cb41b7 allows local users to execute commands through a malicious SVN repository. The omz_urldecode function in lib/functions.zsh converts percent escapes and passes the resulting attacker-controlled text to eval. The documented SVN path requires the svn plugin, a theme that calls svn_prompt_info, checkout of a malicious repository, and entry into a crafted directory.

CVSS severity7.8
High
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

OS command injection in Oh My Zsh before commit 6cb41b7 allows local users to execute commands through a malicious SVN repository. The omz_urldecode function in lib/functions.zsh converts percent escapes and passes the resulting attacker-controlled text to eval. The documented SVN path requires the svn plugin, a theme that calls svn_prompt_info, checkout of a malicious repository, and entry into a crafted directory.

The record

CVE
CVE-2021-3934
Published
Nov 12, 2021
Updated
Aug 3, 2024
Vendor
Oh My Zsh
Product
Oh My Zsh
Classifications
CWE-78, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <6cb41b70a6d04301fd50cd5862ecd705ba226c0e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Oh My Zsh · Oh My Zshversion=unspecified <6cb41b70a6d04301fd50cd5862ecd705ba226c0e

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
7.8Protect AI (formerly huntr.dev)CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
5.1NIST NVDAV:N/AC:H/Au:N/C:P/I:P/A:P

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo