Red Hat Enterprise Linux 10: Improper Certificate Validation
CVE-2026-42013 is a high-severity improper certificate validation vulnerability in Red Hat Enterprise Linux 10 from Red Hat, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.42% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Red Hat Enterprise Linux 10 you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE; 10 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- LowSome restricted data can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N. Scored by CNA (redhat.com).
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Certificate Validation
The product does not validate, or incorrectly validates, a certificate.
How developers prevent this class of flaw
- Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
- If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
More Improper Certificate Validation vulnerabilities (CWE-295)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
- access.redhat.com/errata/RHSA-2026:13274
- access.redhat.com/errata/RHSA-2026:20611
- access.redhat.com/errata/RHSA-2026:20612
- access.redhat.com/errata/RHSA-2026:20613
- access.redhat.com/errata/RHSA-2026:26319
- access.redhat.com/errata/RHSA-2026:26409
- access.redhat.com/errata/RHSA-2026:29197
- access.redhat.com/errata/RHSA-2026:30004
- access.redhat.com/errata/RHSA-2026:30849
- access.redhat.com/errata/RHSA-2026:30850
- access.redhat.com/errata/RHSA-2026:32962
- access.redhat.com/errata/RHSA-2026:33125
- access.redhat.com/errata/RHSA-2026:40762
- access.redhat.com/errata/RHSA-2026:41921
- access.redhat.com/errata/RHSA-2026:43575
Other vulnerabilities in Red Hat Enterprise Linux 10
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.9 High severity
- 7.3 High severity
- 7.5 High severity
Recent Improper Certificate Validation vulnerabilities
- 8.1 High severity
- 8.1 High severity
- 7.1 High severity
- 7.4 High severity
- 9.3 Critical severity
- 8.8 High severity
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