CVE-2026-35387

OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.

OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.

An open source implementation of SSH protocol version 2

Security Fix(es):

Vulnerability in the OpenSSH GSSAPI delta included in various Linux distributions. This vulnerability affects the GSSAPI patches added by various Linux distributions and does not affect the OpenSSH upstream project itself. The usage of sshpkt_disconnect() on an error, which does not terminate the process, allows an attacker to send an unexpected GSSAPI message type during the GSSAPI key exchange to the server, which will call the underlying function and continue the execution of the program without setting the related connection variables. As the variables are not initialized to NULL the code later accesses those uninitialized variables, accessing random memory, which could lead to undefined behavior. The recommended workaround is to use ssh_packet_disconnect() instead, which does terminate the process. The impact of the vulnerability depends heavily on the compiler flag hardening configuration.(CVE-2026-3497)

In OpenSSH before 10.3, a file downloaded by scp may be installed setuid or setgid, an outcome contrary to some users' expectations, if the download is performed as root with -O (legacy scp protocol) and without -p (preserve mode).(CVE-2026-35385)

In OpenSSH before 10.3, command execution can occur via shell metacharacters in a username within a command line. This requires a scenario where the username on the command line is untrusted, and also requires a non-default configurations of % in ssh_config.(CVE-2026-35386)

OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.(CVE-2026-35387)

OpenSSH before 10.3 omits connection multiplexing confirmation for proxy-mode multiplexing sessions.(CVE-2026-35388)

OpenSSH before 10.3 mishandles the authorized_keys principals option in uncommon scenarios involving a principals list in conjunction with a Certificate Authority that makes certain use of comma characters.(CVE-2026-35414)

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)

• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)

• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)

• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)

• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)

• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)

• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)

• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)

• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)

• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)

• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)

• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)

• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)

• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)

• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)

• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)

• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)

• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)

• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)

• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)

• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)
• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)
• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)
• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)
• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)
• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)
• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)
• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)
• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)
• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)
• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)
• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)
• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)
• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)
• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)
• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)
• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• OpenSSH: OpenSSH: Privilege escalation via scp legacy protocol when not preserving file mode (CVE-2026-35385)
• OpenSSH: OpenSSH: Security bypass via mishandling of authorized_keys principals option (CVE-2026-35414)
• OpenSSH: OpenSSH: Information disclosure due to unintended cryptographic algorithm usage (CVE-2026-35387)
• OpenSSH: OpenSSH: Low integrity impact from unconfirmed proxy-mode multiplexing sessions (CVE-2026-35388)
• OpenSSH: OpenSSH: Arbitrary command execution via shell metacharacters in username (CVE-2026-35386)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.

• CVE-2026-35387: correctly match ECDSA signature algorithms against HostKeyAlgorithms, PubkeyAcceptedAlgorithms and HostbasedAcceptedAlgorithms
• CVE-2026-35388: add missing askpass check when using ControlMaster=ask/autoask and "ssh -O proxy ..."
• CVE-2026-35414: fix authorized_keys principals option matching to compare comma-separated entries individually instead of using match_list

• CVE-2026-35387: correctly match ECDSA signature algorithms against HostKeyAlgorithms, PubkeyAcceptedAlgorithms and HostbasedAcceptedAlgorithms
• CVE-2026-35388: add missing askpass check when using ControlMaster=ask/autoask and "ssh -O proxy ..."
• CVE-2026-35414: fix authorized_keys principals option matching to compare comma-separated entries individually instead of using match_list

In OpenSSH before 10.3, a file downloaded by scp may be installed setuid or setgid, an outcome contrary to some users' expectations, if the download is performed as root with -O (legacy scp protocol) and without -p (preserve mode). (CVE-2026-35385) In OpenSSH before 10.3, command execution can occur via shell metacharacters in a username within a command line. This requires a scenario where the username on the command line is untrusted, and also requires a non-default configurations of % in ssh_config. (CVE-2026-35386) OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms. (CVE-2026-35387) OpenSSH before 10.3 omits connection multiplexing confirmation for proxy-mode multiplexing sessions. (CVE-2026-35388) OpenSSH before 10.3 mishandles the authorized_keys principals option in uncommon scenarios involving a principals list in conjunction with a Certificate Authority that makes certain use of comma characters. (CVE-2026-35414)

Florian Kohnhäuser discovered that OpenSSH incorrectly handled shell metacharacters in certain usernames. An attacker could possibly use this issue to execute arbitrary commands when certain non-default configurations were used, resulting in arbitrary code execution. This issue only affected Ubuntu 14.04 LTS. (CVE-2026-35386)

Christos Papakonstantinou discovered that OpenSSH incorrectly handled ECDSA algorithm restrictions. An attacker could possibly use this issue to cause unintended ECDSA algorithms to be accepted, resulting in security restrictions being bypassed. (CVE-2026-35387)

Vladimir Tokarev discovered that OpenSSH incorrectly handled certain principal restrictions in authorized_keys files. An attacker could possibly use this issue to bypass principal restrictions, resulting in unauthorized access. This issue only affected Ubuntu 14.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2026-35414)

It was discovered that OpenSSH incorrectly handled downloaded file paths when using sftp with an untrusted server. An attacker could possibly use this issue to write downloaded files outside the intended location, resulting in unauthorized file modification. (CVE-2026-59995)

It was discovered that OpenSSH incorrectly handled command-line arguments in internal-sftp. An attacker could possibly use this issue to cause certain security-related arguments to be ignored, resulting in security restrictions being bypassed. (CVE-2026-59997)

It was discovered that OpenSSH incorrectly handled GSSAPIStrictAcceptorCheck when used with Windows Active Directory. An attacker could possibly use this issue to bypass GSSAPI security restrictions, resulting in unauthorized access. (CVE-2026-59998)

It was discovered that OpenSSH incorrectly handled forwarding restrictions when DisableForwarding and PermitTunnel were used together. An attacker could possibly use this issue to create tunnels despite forwarding being disabled, resulting in security restrictions being bypassed. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-59999)

It was discovered that OpenSSH incorrectly handled authentication attempt limits when using GSSAPI authentication. An attacker could possibly use this issue to consume excessive system resources, resulting in a denial of service. (CVE-2026-60000)

It was discovered that OpenSSH did not always enforce the minimum authentication delay. An attacker could possibly use this issue to perform authentication attempts more rapidly than intended, resulting in weakened brute-force protections. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-60001)

It was discovered that OpenSSH incorrectly handled certain concurrent remote forwarding operations. An attacker could possibly use this issue to trigger a use-after-free, resulting in a denial of service or arbitrary code execution. (CVE-2026-73282)