Bug 2569161 (CVE-2026-107364)

Summary: CVE-2026-107364 krb5: Unauthenticated KDC DoS based on ASN.1 decoder read overrun
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: unspecifiedCC: abokovoy, jrische, rhel-process-autobot, security-response-team, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: ---
Doc Text:
In all released versions of MIT krb5, an unauthenticated attacker can cause a KDC process to perform a large read overrun, likely causing the process to terminate.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2569307    
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Description OSIDB Bzimport 2026-11-09 14:09:21 UTC 
The KDC decodes requests using the libkrb5 ASN.1 DER decoder, but obtains pointers to subsets of the encoding (such as the KDC-REQ-BODY) via its own fetch_asn1_field().  This utility function does not consider the input length, assumes the tag identifier is a single byte, and supports indefinite length encoding.  The libkrb5 decoder accepts multi-byte tag identifiers and does not enforce minimality of tag identifier encoding.  A request packet crafted using a non-minimal tag identifier can pass through the libkrb5 decoder, but fool fetch_asn1_field() into indefinite length processing, which may send it reading beyond the bounds of the packet.