CVE-2026-106582

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.

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.

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-2026-106587: sshd did not clear AuthorizedPrincipalsFile, TrustedUserCAKeys and Banner when a Match block set them to "none", so the global value stayed in effect before authentication; clear them in the pre-auth part of copy_set_server_options(). Backport upstream commit 526fd277.
• CVE-2026-106586: sshd dropped the authorized_keys "restrict" flag when merging key and certificate options, which could re-enable features such as tunnel forwarding; OR the restricted flag in sshauthopt_merge(). Backport upstream commit 991f1f31.
• CVE-2026-106552: sftp(1) accepted an empty file name from a server directory listing and could pick ".." or the local root as an implicit download destination; reject empty names and map ".." and remote roots to ".". Backport upstream commit c07ea218.
• CVE-2026-106584: ssh-keygen(1) converted certificate validity dates without letting mktime() decide DST, giving expiry times off by an hour; set tm_isdst to -1 in parse_absolute_time(). Backport upstream commit aef20dfe.
• CVE-2026-106582: compressed SSH sessions used the zlib LZ77 dictionary coder, exposing a compression side channel; use Huffman-only compression for outgoing packets. Backport upstream commit 1d5340fc.

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)

It was discovered that OpenSSH's sftp client incorrectly handled paths returned by the server during a recursive copy operation. A remote attacker controlling the server could possibly use this issue to write files to unintended locations. (CVE-2026-106552)

It was discovered that OpenSSH's sshd server incorrectly handled GSSAPIAuthentication state across authentication attempts. An attacker could possibly use this issue to obtain credentials from a previous failed authentication attempt. (CVE-2026-106553, CVE-2026-106555)

It was discovered that OpenSSH incorrectly used an LZ77 dictionary coder during compression. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-106582)

It was discovered that OpenSSH's ssh client incorrectly allowed special characters in command-line usernames. An attacker could possibly use this issue to inject arbitrary commands via specially crafted usernames. (CVE-2026-106583)

It was discovered that OpenSSH's ssh-keygen incorrectly handled Daylight Saving Time when converting dates. An attacker could possibly use this issue to cause certificates to have incorrect expiration times. (CVE-2026-106584)

It was discovered that OpenSSH did not check whether the maximum packet length was exceeded during decompression. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-106585)

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-2026-106586)

It was discovered that OpenSSH's sshd server incorrectly handled certain configuration options that accept a "none" value. An attacker could possibly use this issue to cause OpenSSH to behave unexpectedly. (CVE-2026-106587)

It was discovered that OpenSSH's sftp client incorrectly handled paths returned by the server during a recursive copy operation. A remote attacker controlling the server could possibly use this issue to write files to unintended locations. (CVE-2026-106552)

It was discovered that OpenSSH's sshd server incorrectly handled GSSAPIAuthentication state across authentication attempts. An attacker could possibly use this issue to obtain credentials from a previous failed authentication attempt. (CVE-2026-106553, CVE-2026-106555)

It was discovered that OpenSSH incorrectly used an LZ77 dictionary coder during compression. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-106582)

It was discovered that OpenSSH's ssh client incorrectly allowed special characters in command-line usernames. An attacker could possibly use this issue to inject arbitrary commands via specially crafted usernames. (CVE-2026-106583)

It was discovered that OpenSSH's ssh-keygen incorrectly handled Daylight Saving Time when converting dates. An attacker could possibly use this issue to cause certificates to have incorrect expiration times. (CVE-2026-106584)

It was discovered that OpenSSH did not check whether the maximum packet length was exceeded during decompression. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-106585)

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-2026-106586)

It was discovered that OpenSSH's sshd server incorrectly handled certain configuration options that accept a "none" value. An attacker could possibly use this issue to cause OpenSSH to behave unexpectedly. (CVE-2026-106587)