Vulnerability · Published Jul 30, 2026 · Assigned by redhat
CVE-2026-58218Samba: dns signing dos via tkey name cache exhaustion
Medium 5.3
In plain English
A medium-severity security flaw in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 56% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
A flaw was found in Samba's internal DNS server where unauthenticated TKEY registration requests were added to the TKEY name cache before being rejected. A remote, unauthenticated attacker can exploit this behavior by sending a large number of TKEY requests with arbitrary names, exhausting the cache and evicting legitimate TKEY entries. This can prevent legitimate TSIG authentication for signed DNS queries, resulting in a denial of service.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | samba | no fix listed | DEBIAN-CVE-2026-58218 |
| Debian:13 | samba | 2:4.22.10+dfsg-0+deb13u2 | DEBIAN-CVE-2026-58218 |
| Debian:14 | samba | 2:4.24.5+dfsg-1 | DEBIAN-CVE-2026-58218 |
| Ubuntu:22.04:LTS | samba | 2:4.15.13+dfsg-0ubuntu1.13 | UBUNTU-CVE-2026-58218 |
| Ubuntu:24.04:LTS | samba | 2:4.19.5+dfsg-4ubuntu9.7 | UBUNTU-CVE-2026-58218 |
| Ubuntu:26.04:LTS | samba | 2:4.23.6+dfsg-1ubuntu2.2 | UBUNTU-CVE-2026-58218 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
| Red Hat | Red Hat OpenShift Container Platform 4 | see references |
Weakness: CWE-410 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
References
- https://access.redhat.com/security/cve/CVE-2026-58218 vdb-entry, x_refsource_REDHAT
- RHBZ#2502728 issue-tracking, x_refsource_REDHAT
- https://bugzilla.samba.org/show_bug.cgi?id=16115
- https://www.samba.org/samba/security/CVE-2026-58218.html