Bug 2463368 (CVE-2026-40356)

Summary: CVE-2026-40356 krb5: MIT Kerberos 5 (krb5): Denial of Service via integer underflow and out-of-bounds read
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abokovoy, jrische, rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in MIT Kerberos 5 (krb5). An unauthenticated remote attacker can exploit an integer underflow and an out-of-bounds read vulnerability by calling `gss_accept_sec_context()` on a system with a NegoEx mechanism registered. This can lead to the process terminating, resulting in a Denial of Service (DoS).
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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: 2463395, 2463396, 2463397    
Bug Blocks:    

Description OSIDB Bzimport 2026-04-28 07:02:01 UTC 
In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message.