Unauthenticated TKEY Registration Vulnerability in Samba's DNS Server
CVE-2026-58218

5.3MEDIUM

Key Information:

Vendor

Red Hat
Status
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Vendor
CVE Published:
30 July 2026

What is CVE-2026-58218?

A security flaw exists in Samba's internal DNS server, allowing unauthenticated attackers to exploit the TKEY registration mechanism. By sending numerous TKEY requests with arbitrary names, an attacker can fill the TKEY name cache, causing legitimate entries to be evicted. This disruption can lead to failures in TSIG authentication for signed DNS queries, ultimately resulting in a denial of service for users relying on the DNS server.

References

https://access.redhat.com/security/cve/CVE-2026-58218
vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2502728
issue-trackingx_refsource_REDHAT
https://bugzilla.samba.org/show_bug.cgi?id=16115

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Red Hat would like to thank Andrew Tridgell (Samba Team) and Tristan Madani (Talence Security) for reporting this issue.
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