GnuTLS DTLS DoS via Duplicate Seq Number Reordering
CVE-2026-42009 Published on May 18, 2026
Gnutls: gnutls: denial of service via dtls packet reordering vulnerability
A flaw was found in gnutls. A remote attacker could exploit an issue in the Datagram Transport Layer Security (DTLS) packet reordering logic. The comparator function, responsible for ordering DTLS packets by sequence numbers, did not correctly handle packets with duplicate sequence numbers. This could lead to unstable packet ordering or undefined behavior, resulting in a denial of service.
Vulnerability Analysis
CVE-2026-42009 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Timeline
Reported to Red Hat.
Made public.
Weakness Type
Undefined Behavior for Input to API
The behavior of this function is undefined unless its control parameter is set to a specific value.
Products Associated with CVE-2026-42009
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