Is CVE-2026-21439 in the CISA KEV catalog?

No. CVE-2026-21439 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-21439?

CVE-2026-21439 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2026-21439?

CVE-2026-21439 has an EPSS score of 0.30% (22th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-21439?

Upgrade badkeys to 0.0.16 or later.

CVE & CISA-KEV Catalog

CVE-2026-21439

MEDIUM

5.3

CVSS v3

NVD

Description

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.

CWE-150

How to fix

Remediation Available

badkeysNVD

Affected:< 0.0.16Fixed in:0.0.16CVE-2026-21439derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploit Intelligence

0.30%probability of exploitation in 30 days

22ndpercentile

Low risk: more likely to be exploited than 22% of all known CVEs.

References

Patch2

Exploit1

github.com

Third-Party Advisory1

github.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-01-12.