SB2026090366 - Ubuntu update for openssh

CSH
CYBERSECURITY HELP
Sign In REGISTER

Main Vulnerability Database SB2026090366

SB2026090366 - Ubuntu update for openssh

Published: September 3, 2026

Security Bulletin ID SB2026090366
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 3
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 3 vulnerabilities.


1) Improper access control (CVE-ID: CVE-2026-73281)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to bypass intended local-only restrictions on agent operations.

The vulnerability exists due to improper access control in ssh-agent session binding handling when processing forwarded agent binding requests while the agent is locked. A remote user can send crafted requests through a forwarded agent to bypass intended local-only restrictions on agent operations.

This may permit adding PKCS#11 tokens and using keys with destination restrictions through a forwarded agent.


2) Use-after-free (CVE-ID: CVE-2026-73282)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to use-after-free in the ssh client remote forwarding handling when a remote forwarding is added via the local session multiplexing socket while a remote forwarding open request is pending with the server. A remote user can trigger this race condition to cause a denial of service.

Exploitation requires access to the local session multiplexing socket while a remote forwarding open request is pending.


3) Improper access control (CVE-ID: CVE-2026-73283)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to bypass forwarding restrictions.

The vulnerability exists due to improper access control in sshd authorized_keys restrict keyword enforcement when handling tunnel forwarding. A remote user can use tunnel forwarding despite intended restrictions to bypass forwarding restrictions.

Tunnel forwarding is administratively disabled by default.


Remediation

Install update from vendor's website.

References