CVE-2021-31799

Arbitrary command execution via pipe-prefixed tags filenames

Published Jul 29, 2021 · Updated Oct 15, 2024

OS command injection in RDoc 3.11 through 6.3.0 allows local users to execute arbitrary commands through a crafted project filename. The remove_unparseable method passes tags-suffixed filenames to Kernel#open, which treats a leading pipe as a command stream and invokes the trailing shell command. Exploitation requires a user to run rdoc on an attacker-controlled Ruby project, and commands execute with that user's privileges.

CVSS severity7.0
High
EPSS probability1.48%
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 RDoc 3.11 through 6.3.0 allows local users to execute arbitrary commands through a crafted project filename. The remove_unparseable method passes tags-suffixed filenames to Kernel#open, which treats a leading pipe as a command stream and invokes the trailing shell command. Exploitation requires a user to run rdoc on an attacker-controlled Ruby project, and commands execute with that user's privileges.

The record

CVE
CVE-2021-31799
Published
Jul 29, 2021
Updated
Oct 15, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-78, T1204.002
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 15, 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.0NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.4NIST NVDAV:L/AC:M/Au:N/C:P/I:P/A:P
7.0CISA-ADPCVSS:3.1/AV:L/AC:H/PR:L/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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