CVE-2021-45444

Arbitrary command execution via recursive prompt substitution

Published Feb 13, 2022 · Updated Aug 4, 2024

Command injection in Zsh before 5.8.1 allows context-dependent attackers to execute arbitrary commands through crafted prompt data. Prompt escape sequences such as %F recursively apply PROMPT_SUBST to their arguments, so command output embedded in a prompt is evaluated as shell code. Exploitation requires PROMPT_SUBST, a prompt configuration that incorporates attacker-controlled output, and user interaction such as checking out a crafted Git branch.

CVSS severity7.8
High
EPSS probability1.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Zsh before 5.8.1 allows context-dependent attackers to execute arbitrary commands through crafted prompt data. Prompt escape sequences such as %F recursively apply PROMPT_SUBST to their arguments, so command output embedded in a prompt is evaluated as shell code. Exploitation requires PROMPT_SUBST, a prompt configuration that incorporates attacker-controlled output, and user interaction such as checking out a crafted Git branch.

The record

CVE
CVE-2021-45444
Published
Feb 13, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-167, T1059.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 13, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-167Improper Handling of Additional Special Element
T1059.004Command and Scripting Interpreter: Unix Shell

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

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Your stack

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