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SSH CVE-2026-21439

MEDIUM
Improper Neutralization of Escape, Meta, or Control Sequences (CWE-150)
2026-01-06 security-advisories@github.com GHSA-wjpc-4f29-83h3
5.3
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

Lifecycle Timeline

4
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
PoC Detected
Jan 12, 2026 - 18:18 vuln.today
Public exploit code
Patch released
Jan 12, 2026 - 18:18 nvd
Patch available
CVE Published
Jan 06, 2026 - 00:15 nvd
MEDIUM 5.3

DescriptionGitHub Advisory

badkeys is a tool and library for checking cryptographic public keys for known vulnerabilities. In versions 0.0.15 and below, an attacker may inject content with ASCII control characters like vertical tabs, ANSI escape sequences, etc., that can create misleading output of the badkeys command-line tool. This impacts scanning DKIM keys (both --dkim and --dkim-dns), SSH keys (--ssh-lines mode), and filenames in various modes. This issue is fixed in version 0.0.16.

AnalysisAI

badkeys is a tool and library for checking cryptographic public keys for known vulnerabilities. [CVSS 5.3 MEDIUM]

Technical ContextAI

Affects Badkeys. badkeys is a tool and library for checking cryptographic public keys for known vulnerabilities. In versions 0.0.15 and below, an attacker may inject content with ASCII control characters like vertical tabs, ANSI escape sequences, etc., that can create misleading output of the badkeys command-line tool. This impacts scanning DKIM keys (both --dkim and --dkim-dns), SSH keys (--ssh-lines mode), and filenames in various modes. This issue is fixed in version 0.0.16.

RemediationAI

A vendor patch is available — apply it immediately. Fixed in version 0.0.16.. Restrict network access to the affected service where possible.

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CVE-2026-21439 vulnerability details – vuln.today

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