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CVE-2026-21439

badkeys vulnerable to ASCII control character injection on console via malformed input

2.0 LowFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

0.33%Up 0.3 points since Jan 6, 2026
90%50%10%1%

What each source reports

CVE List Score used 2.0

badkeys vulnerable to ASCII control character injection on console via malformed input

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.

Record
CVE-2026-21439
CVSS 4.0
2.0 LowCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Weakness
CWE-150
Updated
2026-11-02
EUVDEUVD-2026-0823 2.0

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.

Record
EUVD-2026-0823
CVSS 4.0
2.0 LowCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Updated
2026-11-02
GitHub AdvisoriesGHSA-wjpc-4f29-83h3 2.0

badkeys vulnerable to ASCII control character injection on console via malformed input

Impact

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.

Patches

This has been fixed with the following commits: https://github.com/badkeys/badkeys/commit/de631f69f040974bb5fb442cdab9a1d904c64087 https://github.com/badkeys/badkeys/commit/635a2f3b1b50a895d8b09ec8629efc06189f349a

All users should upgrade badkeys to version 0.0.16.

Resources

https://github.com/badkeys/badkeys/issues/40

Record
GHSA-wjpc-4f29-83h3
CVSS 4.0
2.0 LowCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Weakness
CWE-150
Updated
2026-11-02
NVD 2.0

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.

Record
CVE-2026-21439
CVSS 4.0
2.0 LowCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-150
Updated
2026-11-02
OSV 2.0

badkeys vulnerable to ASCII control character injection on console via malformed input

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.

Record
CVE-2026-21439
CVSS 4.0
2.0 LowCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Weakness
CWE-150
Updated
2026-11-02
OSVGHSA-wjpc-4f29-83h3 2.0

badkeys vulnerable to ASCII control character injection on console via malformed input

Impact

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.

Patches

This has been fixed with the following commits: https://github.com/badkeys/badkeys/commit/de631f69f040974bb5fb442cdab9a1d904c64087 https://github.com/badkeys/badkeys/commit/635a2f3b1b50a895d8b09ec8629efc06189f349a

All users should upgrade badkeys to version 0.0.16.

Resources

https://github.com/badkeys/badkeys/issues/40

Record
GHSA-wjpc-4f29-83h3
CVSS 4.0
2.0 LowCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Weakness
CWE-150
Updated
2026-11-02
OSVPYSEC-2026-1212 2.0

badkeys vulnerable to ASCII control character injection on console via malformed input

Impact

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.

Patches

This has been fixed with the following commits: https://github.com/badkeys/badkeys/commit/de631f69f040974bb5fb442cdab9a1d904c64087 https://github.com/badkeys/badkeys/commit/635a2f3b1b50a895d8b09ec8629efc06189f349a

All users should upgrade badkeys to version 0.0.16.

Resources

https://github.com/badkeys/badkeys/issues/40

Record
PYSEC-2026-1212
CVSS 4.0
2.0 LowCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
badkeys
PyPI
 through 0.0.15
0.0.16
badkeys
PyPI
 before 0.0.16, plus listed versions
0.0.10.0.100.0.110.0.120.0.13
Show 10 moreShow less
0.0.140.0.150.0.20.0.30.0.40.0.50.0.60.0.70.0.80.0.9
0.0.16

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-21439 is a low vulnerability (CVSS 2.0) in Badkeys, published January 5, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.33%, the 26th percentile. Fixed in badkeys 0.0.16.

References

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