Bug 2524300 (CVE-2026-19401)

Summary: CVE-2026-19401 nsd: NSD: Remote denial of service via crafted DNS Cookie options
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in NSD. A remote attacker can crash an NSD server child by sending a specially crafted message containing a specific number of DNS Cookie options. This continuous crashing can severely hamper or deny DNS service, leading to a denial of service (DoS) condition. This vulnerability primarily affects debugging or non-release build types of NSD.
Story Points: ---
Clone Of: Environment:
Last Closed: 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: 2524355, 2524356    
Bug Blocks:    

Description OSIDB Bzimport 2026-08-26 08:53:14 UTC
Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.