CVE-2026-42013
CVE-2026-42013 is a high-severity vulnerability with a CVSS 3.x base score of 8.2. 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-295.
Key facts
- Severity: High (CVSS 3.x base score 8.2)
- EPSS exploit prediction: 0% (34th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-32011
- Weakness: CWE-295
- Published:
- Last modified:
Description
A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.
Frequently asked questions
- What is CVE-2026-42013?
- A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.
- How severe is CVE-2026-42013?
- CVE-2026-42013 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.
- Is CVE-2026-42013 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-42013?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-42013 have an EU (EUVD) identifier?
- Yes. CVE-2026-42013 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32011.
- When was CVE-2026-42013 published?
- CVE-2026-42013 was published on 2026-05-26 and last updated on 2026-06-30.
References
- https://access.redhat.com/errata/RHSA-2026:20611
- https://access.redhat.com/errata/RHSA-2026:20612
- https://access.redhat.com/errata/RHSA-2026:20613
- https://access.redhat.com/errata/RHSA-2026:26319
- https://access.redhat.com/errata/RHSA-2026:26409
- https://access.redhat.com/errata/RHSA-2026:29197
- https://access.redhat.com/errata/RHSA-2026:30004
- https://access.redhat.com/errata/RHSA-2026:30849
- https://access.redhat.com/errata/RHSA-2026:30850
- https://access.redhat.com/errata/RHSA-2026:32962
- https://access.redhat.com/errata/RHSA-2026:33125
- https://access.redhat.com/security/cve/CVE-2026-42013
- https://bugzilla.redhat.com/show_bug.cgi?id=2467448
- https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-8
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