CVE-2026-73283

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.

An open source implementation of SSH protocol version 2

Security Fix(es):

In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent.(CVE-2026-73282)

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.(CVE-2026-73283)

An open source implementation of SSH protocol version 2

Security Fix(es):

In ssh-agent in OpenSSH before 10.5, some operations can occur remotely but were intended to occur only locally, including operations that add tokens or use keys. This is caused by misinteraction between agent locking and the (CVE-2026-73281)

In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent.(CVE-2026-73282)

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.(CVE-2026-73283)

An open source implementation of SSH protocol version 2

Security Fix(es):

In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent.(CVE-2026-73282)

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.(CVE-2026-73283)

An open source implementation of SSH protocol version 2

Security Fix(es):

In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent.(CVE-2026-73282)

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.(CVE-2026-73283)

An open source implementation of SSH protocol version 2

Security Fix(es):

In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent.(CVE-2026-73282)

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.(CVE-2026-73283)

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: sftp client allows attacker to control downloaded file location (CVE-2026-59995)

• openssh: OpenSSH sshd: Security bypass due to incorrect handling of forwarding and tunneling options (CVE-2026-59999)

• openssh: OpenSSH: Tunnel forwarding restriction bypass (CVE-2026-73283)

• openssh: OpenSSH: ssh-agent allows remote execution of local operations (CVE-2026-73281)

• openssh: OpenSSH: Information disclosure and data corruption via use-after-free in ssh client (CVE-2026-73282)

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: sftp client allows attacker to control downloaded file location (CVE-2026-59995)

• openssh: OpenSSH sshd: Security bypass due to incorrect handling of forwarding and tunneling options (CVE-2026-59999)

• openssh: OpenSSH: Tunnel forwarding restriction bypass (CVE-2026-73283)

• openssh: OpenSSH: ssh-agent allows remote execution of local operations (CVE-2026-73281)

• openssh: OpenSSH: Information disclosure and data corruption via use-after-free in ssh client (CVE-2026-73282)

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: SFTP security bypass due to command-line argument parsing flaw (CVE-2026-59997)

• openssh: OpenSSH: Undocumented GSSAPIStrictAcceptorCheck behavior impacts security in Windows Active Directory (CVE-2026-59998)

• openssh: OpenSSH: Brute-force attacks facilitated due to insufficient authentication delay (CVE-2026-60001)

• openssh: OpenSSH: Denial of Service via excessive GSSAPI authentication attempts (CVE-2026-60000)

• openssh: OpenSSH: Tunnel forwarding restriction bypass (CVE-2026-73283)

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.

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.

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: sftp client allows attacker to control downloaded file location (CVE-2026-59995)
• openssh: OpenSSH sshd: Security bypass due to incorrect handling of forwarding and tunneling options (CVE-2026-59999)
• openssh: OpenSSH: Tunnel forwarding restriction bypass (CVE-2026-73283)
• openssh: OpenSSH: ssh-agent allows remote execution of local operations (CVE-2026-73281)
• openssh: OpenSSH: Information disclosure and data corruption via use-after-free in ssh client (CVE-2026-73282)

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: sftp client allows attacker to control downloaded file location (CVE-2026-59995)
• openssh: OpenSSH sshd: Security bypass due to incorrect handling of forwarding and tunneling options (CVE-2026-59999)
• openssh: OpenSSH: Tunnel forwarding restriction bypass (CVE-2026-73283)
• openssh: OpenSSH: ssh-agent allows remote execution of local operations (CVE-2026-73281)
• openssh: OpenSSH: Information disclosure and data corruption via use-after-free in ssh client (CVE-2026-73282)

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: SFTP security bypass due to command-line argument parsing flaw (CVE-2026-59997)
• openssh: OpenSSH: Undocumented GSSAPIStrictAcceptorCheck behavior impacts security in Windows Active Directory (CVE-2026-59998)
• openssh: OpenSSH: Brute-force attacks facilitated due to insufficient authentication delay (CVE-2026-60001)
• openssh: OpenSSH: Denial of Service via excessive GSSAPI authentication attempts (CVE-2026-60000)
• openssh: OpenSSH: Tunnel forwarding restriction bypass (CVE-2026-73283)

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.

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.

• SECURITY UPDATE: use-after-free in the ssh client when a remote forwarding is added over the multiplexing socket
  • debian/patches/CVE-2026-73282.patch: pass a heap-allocated index instead of a pointer into options.remote_forwards[] to ssh_confirm_remote_forward() in ssh.c, so a concurrent add_remote_forward() reallocation cannot leave the pending global request confirmation holding a dangling pointer.
  • CVE-2026-73282
• SECURITY UPDATE: authorized_keys restrict keyword did not cover tunnel forwarding
  • debian/patches/CVE-2026-73283.patch: also reject tunnel device forwarding in server_request_tun() (serverloop.c) when the authenticating key carries the restrict option.
  • CVE-2026-73283

• CVE-2026-73283: make the authorized_keys restrict keyword apply to tunnel forwarding by rejecting tun/tap requests when auth_opts->restricted is set in server_request_tun(); backport upstream d322f2cc verbatim. The new term is inert until sshauthopt_merge() preserves restricted, which upstream does not yet do either -- see the patch header

• CVE-2026-73282: ssh(1) use-after-free: a pending remote-forward global confirmation held a raw pointer into options.remote_forwards, which a forwarding added concurrently over the multiplexing socket could realloc away; carry the forwarding index in the callback context and resolve the entry at callback time. Backport upstream commit 9910d5ef.
• CVE-2026-73283: sshd did not apply the authorized_keys 'restrict' keyword to tunnel-device forwarding; also reject tun forwarding in server_request_tun() when the key is restricted. Backport upstream commit d322f2cc.

Local mitm of x11 forwarding via abstract unix socket pre-binding in Red Hat Enterprise Linux openssh client versions. (CVE-2026-55655) sftp in OpenSSH before 10.4 does not properly constrain the location of downloaded files when "sftp server:/path ." is used with an attacker-controlled server. (CVE-2026-59995) scp in OpenSSH before 10.4 may place a file in the parent directory of an intended directory when the copy occurs between two remote destinations. (CVE-2026-59996) internal-sftp in sshd in OpenSSH before 10.4 recognizes only the first 9 command-line arguments, which can be important if a later command-line argument would have helped to ensure the intended security properties of an SFTP connection. (CVE-2026-59997) sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has no value if the server is in Windows Active Directory. (CVE-2026-59998) In sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over PermitTunnel=yes, but did not. (CVE-2026-59999) sshd in OpenSSH before 10.4 allows remote attackers to cause a denial of service (resource consumption from excessive authentication attempts) because MaxAuthTries was mishandled for GSSAPIAuthentication. (CVE-2026-60000) sshd in OpenSSH before 10.4 does not always honor the minimum authentication delay. (CVE-2026-60001) ssh in OpenSSH before 10.4 can have a use-after-free when a server changes its host key during a key re-exchange. (This outcome occurs only on the client side.). (CVE-2026-60002) In ssh-agent in OpenSSH before 10.5, some operations can occur remotely but were intended to occur only locally, including operations that add tokens or use keys. This is caused by misinteraction between agent locking and the [email protected] extension. (CVE-2026-73281) In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent. (CVE-2026-73282) In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not. (CVE-2026-73283) In sftp in OpenSSH before 10.6, a server can trigger directory traversal (causing files to be written to unintended locations) during a recursive copy operation. (CVE-2026-106552) In sshd in OpenSSH before 10.6, credentials can incorrectly persist after failure of a GSSAPIAuthentication authentication attempt. (CVE-2026-106553) In sshd in OpenSSH before 10.6, GSSAPIAuthentication authentication state can incorrectly be persisted across authentication attempts. (CVE-2026-106555) In sshd and ssh in OpenSSH before 10.6, an LZ77 dictionary coder can be used even though this is contraindicated by the arXiv 2609.07709 "Crossing the Streams" findings. (CVE-2026-106582) In ssh in OpenSSH before 10.6, a $ or \ character can occur in a command-line username, leading to injection. (CVE-2026-106583) In ssh-keygen in OpenSSH before 10.6, certificates could have incorrect expiration times because of Daylight Saving mishandling. There can be a slightly more severe effect on users in certain Antarctic locations. (CVE-2026-106584) In sshd and ssh in OpenSSH before 10.6, there is no check for whether the maximum packet length is exceeded during decompression of highly compressed data. (CVE-2026-106585) In sshd in OpenSSH before 10.6, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not, a different vulnerability than CVE-2026-73283. (CVE-2026-106586) In sshd in OpenSSH before 10.6, the value "none" for a configuration option is sometimes interpreted as a filename but was intended to mean that a feature is disabled. (CVE-2026-106587)

This update for openssh fixes the following issues:

• CVE-2026-73281: refused binding requests on locked SSH agents can allow destination restriction bypasses (bsc#1275075).
• CVE-2026-73282: unsynchronized remote forwarding updates in SSH client multiplexing can cause use-after-free (bsc#1275074).
• CVE-2026-73283: unenforced restriction keywords on tunnel forwarding can allow administrative security policy bypasses (bsc#1275079).

This update for openssh fixes the following issues:

• CVE-2026-59995: sftp: a malicious server could change the the location of downloaded files (bsc#1271044).
• CVE-2026-59996: scp: a malicious server could write files to the parent directory of the intended target directory (bsc#1271046).
• CVE-2026-59997: sshd: internal-sftp command lines are silently truncated after the 9th argument (bsc#1271048).
• CVE-2026-59998: sshd: Undocumented GSSAPIStrictAcceptorCheck behavior impacts security in Windows Active Directory (bsc#1271049).
• CVE-2026-59999: sshd: DisableForwarding=yes didn't override PermitTunnel=yes (bsc#1271052).
• CVE-2026-60000: sshd: pre-authentication denial of service when GSSAPIAuthentication is enabled (bsc#1271053).
• CVE-2026-60001: sshd: honor the minimum authentication delay (bsc#1271054).
• CVE-2026-60002: ssh: client-side use-after-free when a server changes its host key during a key reexchange (bsc#1271055).
• CVE-2026-73281: refused binding requests on locked SSH agents can allow destination restriction bypasses (bsc#1275075).
• CVE-2026-73282: unsynchronized remote forwarding updates in SSH client multiplexing can cause use-after-free (bsc#1275074).
• CVE-2026-73283: unenforced restriction keywords on tunnel forwarding can allow administrative security policy bypasses (bsc#1275079).

This update for openssh8.4 fixes the following issues:

• CVE-2026-73282: unsynchronized remote forwarding updates in SSH client multiplexing can cause use-after-free (bsc#1275074).
• CVE-2026-73283: unenforced restriction keywords on tunnel forwarding can allow administrative security policy bypasses (bsc#1275079).

This update for openssh fixes the following issues:

• CVE-2026-73282: unsynchronized remote forwarding updates in SSH client multiplexing can cause use-after-free (bsc#1275074).
• CVE-2026-73283: unenforced restriction keywords on tunnel forwarding can allow administrative security policy bypasses (bsc#1275079).

This update for openssh fixes the following issues:

• CVE-2026-73282: unsynchronized remote forwarding updates in SSH client multiplexing can cause use-after-free (bsc#1275074).
• CVE-2026-73283: unenforced restriction keywords on tunnel forwarding can allow administrative security policy bypasses (bsc#1275079).

This update for openssh fixes the following issues:

• CVE-2026-73281: refused binding requests on locked SSH agents can allow destination restriction bypasses (bsc#1275075).
• CVE-2026-73282: unsynchronized remote forwarding updates in SSH client multiplexing can cause use-after-free (bsc#1275074).
• CVE-2026-73283: unenforced restriction keywords on tunnel forwarding can allow administrative security policy bypasses (bsc#1275079).

Changes for openssh:

• Included mentions of the configuration drop-in directories (bsc#1259462).

It was discovered that OpenSSH's ssh-agent incorrectly handled interactions between agent locking and the [email protected] 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)