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[USN-8621-1] Samba vulnerabilities

Posted on 28 July 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8621-1
July 28, 2026

samba vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

Several security issues were fixed in Samba.

Software Description:
- samba: SMB/CIFS file, print, and login server for Unix

Details:

It was discovered that Samba's pam_winbind incorrectly handled home
directory ownership when mkhomedir was enabled. A local attacker could
possibly use this issue to cause a denial of service by triggering a change
in ownership of the root directory. (CVE-2026-15779)

Arjun Basnet, Douglas Bagnall, and Andrew Tridgell discovered that Samba
incorrectly handled TSIG packets with name compression. A remote attacker
could possibly use this issue to cause Samba to crash, resulting in a
denial of service. (CVE-2026-6949)

Tristan Madani discovered that Samba incorrectly handled malformed ASN.1
kpasswd packets. An authenticated user could possibly use this issue to
cause Samba to crash, resulting in a denial of service. (CVE-2026-58216)

Andrew Tridgell and Tristan Madani discovered that Samba incorrectly
handled TKEY name registration. A remote attacker could possibly use this
issue to exhaust the TKEY name cache, resulting in a denial of service.
(CVE-2026-58218)

It was discovered that Samba incorrectly handled internal LDB special
directory names when processing authenticated LDAP requests. An
authenticated user could possibly use this issue to perform unauthorized
modifications and gain control of a domain. (CVE-2026-58221)

Andrew Tridgell and Tristan Madani discovered that Samba incorrectly
handled LDAP Compare requests. An authenticated user could possibly use
this issue to obtain sensitive information. (CVE-2026-58222)

Tristan Madani, Andrew Tridgell, and Martin Schwenke discovered that the
CTDB protocol in Samba had insufficient bounds checking. A remote attacker
could possibly use this issue to cause Samba to crash, resulting in a
denial of service. (CVE-2026-58224)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
samba 2:4.23.6+dfsg-1ubuntu2.2

Ubuntu 24.04 LTS
samba 2:4.19.5+dfsg-4ubuntu9.7

Ubuntu 22.04 LTS
samba 2:4.15.13+dfsg-0ubuntu1.13

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8621-1
CVE-2026-15779, CVE-2026-58216, CVE-2026-58218, CVE-2026-58221,
CVE-2026-58222, CVE-2026-58224, CVE-2026-6949

Package Information:
https://launchpad.net/ubuntu/+source/samba/2:4.23.6+dfsg-1ubuntu2.2
https://launchpad.net/ubuntu/+source/samba/2:4.19.5+dfsg-4ubuntu9.7
https://launchpad.net/ubuntu/+source/samba/2:4.15.13+dfsg-0ubuntu1.13

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