CVE-2026-21439
CVE-2026-21439 is a medium-severity vulnerability in Badkeys with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-150.
Key facts
- Severity: Medium (CVSS 3.x base score 5.3)
- CVSS v4: 2.0
- EPSS exploit prediction: 0% (22nd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-0823
- Weakness: CWE-150
- Affected product: Badkeys
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-21439?
- 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.
- How severe is CVE-2026-21439?
- CVE-2026-21439 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
- Is CVE-2026-21439 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-21439?
- CVE-2026-21439 affects Badkeys. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-21439?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-21439 have an EU (EUVD) identifier?
- Yes. CVE-2026-21439 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-0823.
- When was CVE-2026-21439 published?
- CVE-2026-21439 was published on 2026-01-06 and last updated on 2026-06-17.
References
- https://github.com/badkeys/badkeys/commit/635a2f3b1b50a895d8b09ec8629efc06189f349a
- https://github.com/badkeys/badkeys/commit/de631f69f040974bb5fb442cdab9a1d904c64087
- https://github.com/badkeys/badkeys/issues/40
- https://github.com/badkeys/badkeys/security/advisories/GHSA-wjpc-4f29-83h3
Affected products (1)
- cpe:2.3:a:badkeys:badkeys:*:*:*:*:*:python:*:*
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