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Ubuntu Security NoticesUSN-8721-1

USN-8721-1: OpenSSH vulnerabilities

It was discovered that OpenSSH's ssh-agent incorrectly handled interactions between agent locking and the session-bind@openssh.com extension. A remote attacker with access to a forwarded agent connection could possibly use this issue to perform operations that should only be available locally, such as adding tokens or using keys. (CVE-2026-73281) It was discovered that OpenSSH's ssh client incorrectly handled concurrent remote-forwarding operations. A remote attacker could possibly use this issue to cause a use-after-free condition, resulting in a denial of service or the execution of arbitrary code. (CVE-2026-73282) It was discovered that OpenSSH's sshd server incorrectly applied the restrict keyword from authorized_keys to tunnel forwarding requests. A local attacker with an authorized key could possibly use this issue to bypass intended tunnel forwarding restrictions. (CVE-2026-73283)

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Scope

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  1. Published by Ubuntu

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  2. Added to SecurityAlert

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  3. Confirmed at the source

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Vulnerabilities

CVEs named in this advisory

CVE-2026-73281View CVSS, KEV, EPSS, and threat contextCVE-2026-73282View CVSS, KEV, EPSS, and threat contextCVE-2026-73283View CVSS, KEV, EPSS, and threat context
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