Bug 2502721 (CVE-2026-58216)

Summary: CVE-2026-58216 samba: kpasswd service: kpasswd packet that contains malformed ASN.1 might cause the server to access 6 bytes of unallocated memory leading server to crash
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, security-response-team, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
An out-of-bounds read flaw was found in Samba's Kerberos Key Distribution Center's (KDC) password change (kpasswd) service. When processing malformed ASN.1-encoded Kerberos password change request, Samba server miscalculates the structure size and attempts to read up to six bytes beyond the end of the allocated buffer. While this out-of-bounds read typically results in a harmless decryption failure, if the read hits unmapped memory, it causes the KDC process to crash. An authenticated attacker can send a specially crafted kpasswd request containing malformed ASN.1 data to trigger the out-of-bounds read, which may cause the KDC process to terminate, resulting in a denial of service.
 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: 2510884    
Bug Blocks:    
Deadline: 2026-07-28   

Description OSIDB Bzimport 2026-07-20 10:46:55 UTC 
A miscalculation means an ASN.1 structure used in a Kerberos password change is assumed to be six bytes bigger than it is. This does not affect ordinary packets (the ASN.1 itself contains the correct size), but a crafted ANS1 packet could force up to six unallocated bytes to be read. The usual outcome of this will be a decryption failure and an error message, but it could make the server process crash.