CVE-2022-4170Public exploitNetwork attack vector

Code execution via unescaped background OSC values

Published Dec 9, 2022 · Updated Apr 14, 2025

Code injection in rxvt-unicode 9.25 and 9.26 allows remote attackers to execute arbitrary code via crafted terminal output. The Perl background extension's on_osc_seq handler embeds OSC 705 and OSC 20 values in a string passed to eval, while q0 fails to escape backslashes and Perl delimiters. Execution requires the background extension, which autoloads with resources such as transparent, and control of data written to the terminal; code runs in the urxvt process.

CVSS severity9.8
Critical
EPSS probability2.06%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in rxvt-unicode 9.25 and 9.26 allows remote attackers to execute arbitrary code via crafted terminal output. The Perl background extension's on_osc_seq handler embeds OSC 705 and OSC 20 values in a string passed to eval, while q0 fails to escape backslashes and Perl delimiters. Execution requires the background extension, which autoloads with resources such as transparent, and control of data written to the terminal; code runs in the urxvt process.

The record

CVE
CVE-2022-4170
Published
Dec 9, 2022
Updated
Apr 14, 2025
Vendor
Marc Lehmann
Product
rxvt-unicode
Classifications
CWE-74, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 9, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 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=rxvt-unicode 9.30

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Marc Lehmann · rxvt-unicodeversion=rxvt-unicode 9.30

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.

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

No observations available

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

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1203Exploitation for Client Execution

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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