Bug 2524373

Summary: CVE-2026-13321 dhcp: DNSSEC Validation Bypass via Out-of-Zone NSEC Next Field [fedora-all]
Product: [Fedora] Fedora Reporter: Thomas Eagle <teagle>
Component: dhcpAssignee: Martin Osvald 🛹 <mosvald>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: fhrdina, jorton, mosvald, pavel, pemensik
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["b4a88e03-41e7-409c-9b8d-e07801865973"]}
Fixed In Version: Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-09-14 10:26:41 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2504166    

Description Thomas Eagle 2026-08-26 12:31:48 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

The resolver accepts validly-signed NSEC records where the "Next
  Domain Name" field points outside the signer's zone. An attacker
  controlling ANY DNSSEC-signed zone can craft NSEC records spanning
  into victim zones, enabling cross-zone cache poisoning with AD=1
  (Authenticated Data flag set)
Comment 1 Martin Osvald 🛹 2026-09-14 10:26:41 UTC 
ISC DHCP is not affected by CVE-2026-13321. This is a BIND server-side DNSSEC validation issue; ISC DHCP does not perform DNSSEC validation.

ISC DHCP uses portions of the ISC BIND libraries (primarily libdns, omapi, and libisccfg) only to support DDNS (TSIG support, DNS message construction/parsing, DHCID generation), OMAPI-related operations, and basic functions (configuration handling, data structures, logging, networking primitives).