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OpenSSH Security Risk: Crash or Code Execution
USN-8090-2
Summary
OpenSSH has security issues that could allow a remote attacker to crash the service or execute malicious code on a server. This affects Ubuntu 20.04 LTS. Update your OpenSSH to the latest version to address these risks.
What to do
- Update canonical openssh to version 1:8.2p1-4ubuntu0.13+esm1.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| canonical | openssh | <= 1:8.2p1-4ubuntu0.13+esm1 | 1:8.2p1-4ubuntu0.13+esm1 |
Original title
openssh vulnerabilities
Original description
USN-8090-1 fixed vulnerabilities in OpenSSH. This update provides the
corresponding updates for Ubuntu 20.04 LTS.
Original advisory details:
Jeremy Brown discovered that the OpenSSH GSSAPI Key Exchange incorrectly
handled disconnecting clients. In non-default configurations where the
GSSAPIKeyExchange setting is enabled, a remote attacker could use this
issue to cause OpenSSH to crash, resulting in a denial of service, or
possibly execute arbitrary code. (CVE-2026-3497)
David Leadbeater discovered that OpenSSH incorrectly handled certain
control characters in usernames. When untrusted usernames and the
ProxyCommand are being used, an attacker could possibly use this issue to
execute arbitrary code. (CVE-2025-61984)
David Leadbeater discovered that OpenSSH incorrectly handled NULL
characters in ssh:// URIs. When the ProxyCommand is being used, an attacker
could possibly use this issue to execute arbitrary code. (CVE-2025-61985)
corresponding updates for Ubuntu 20.04 LTS.
Original advisory details:
Jeremy Brown discovered that the OpenSSH GSSAPI Key Exchange incorrectly
handled disconnecting clients. In non-default configurations where the
GSSAPIKeyExchange setting is enabled, a remote attacker could use this
issue to cause OpenSSH to crash, resulting in a denial of service, or
possibly execute arbitrary code. (CVE-2026-3497)
David Leadbeater discovered that OpenSSH incorrectly handled certain
control characters in usernames. When untrusted usernames and the
ProxyCommand are being used, an attacker could possibly use this issue to
execute arbitrary code. (CVE-2025-61984)
David Leadbeater discovered that OpenSSH incorrectly handled NULL
characters in ssh:// URIs. When the ProxyCommand is being used, an attacker
could possibly use this issue to execute arbitrary code. (CVE-2025-61985)
- https://ubuntu.com/security/notices/USN-8090-2 Vendor Advisory
- https://ubuntu.com/security/CVE-2025-61984 Third Party Advisory
- https://ubuntu.com/security/CVE-2025-61985 Third Party Advisory
- https://ubuntu.com/security/CVE-2026-3497 Third Party Advisory
Published: 12 Mar 2026 · Updated: 13 Mar 2026 · First seen: 13 Mar 2026