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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.

PUBLISHED Reserved 2026-04-23 | Published 2026-05-26 | Updated 2026-06-02 | Assigner redhat




HIGH: 8.2CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

Problem types

Improper Validation of Specified Quantity in Input

Product status

Default status
affected

0:3.8.10-4.el10_2 (rpm) before *
unaffected

Default status
affected

0:3.6.16-8.el8_10.6 (rpm) before *
unaffected

Default status
affected

0:3.6.16-8.el8_10.6 (rpm) before *
unaffected

Default status
affected

0:3.8.10-4.el9_8 (rpm) before *
unaffected

Default status
affected

0:3.8.10-4.el9_8 (rpm) before *
unaffected

Default status
unknown

Default status
affected

Default status
affected

Default status
affected

Timeline

2026-05-06:Reported to Red Hat.
2026-04-29:Made public.

Credits

Red Hat would like to thank Haruto Kimura (Stella) and Joshua Rogers (AISLE Research Team) for reporting this issue.

References

access.redhat.com/errata/RHSA-2026:20611 (RHSA-2026:20611) vendor-advisory

access.redhat.com/errata/RHSA-2026:20612 (RHSA-2026:20612) vendor-advisory

access.redhat.com/errata/RHSA-2026:20613 (RHSA-2026:20613) vendor-advisory

access.redhat.com/security/cve/CVE-2026-42013 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2467448 (RHBZ#2467448) issue-tracking

cve.org (CVE-2026-42013)

nvd.nist.gov (CVE-2026-42013)

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