Actively exploited in the wild
OpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability
OpenBSD - OpenSSH · Listed in the CISA KEV since 2026-11-09. This indicates confirmed attacks in production environments.
Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CVE-2026-123158
HighCVSS 8.1KEVExploitation Probability (EPSS)
Elevated risk63th percentile - higher than 63% of all known CVEs
Summary
sshd in OpenSSH before 10.6p2 on Linux, when musl libc is used without PAM, lacks a workaround for a password authentication bypass (related to misinterpretation of whether a string is intended to be a password hash). For some configurations of accounts, any password between 256 and 1024 characters succeeds. An example of a platform using musl libc without PAM is Alpine Linux.
Risk Assessment
A remote attacker can gain unauthorized access to an account by supplying any password of the appropriate length, potentially leading to full system compromise. The risk affects systems running OpenSSH before 10.6p2 on musl libc without PAM, such as Alpine Linux.
Recommendation
Upgrade OpenSSH to version 10.6p2 or later. Until patched, restrict access to sshd, consider disabling password authentication, and verify account configuration on musl libc platforms without PAM.
Other vulnerabilities in OpenSSH
See all- CVE-2016-6515High
The auth_password function in sshd in OpenSSH before version 7.3 does not limit password lengths for authentication, allowing remote attackers to cause a denial of service via long strings.
- CVE-2015-8325High
The do_setup_env function in sshd in OpenSSH through 7.2p2, when the UseLogin feature is enabled and PAM is configured to read .pam_environment files in user home directories, allows local users to gain privileges by triggering a crafted environment for the /bin/login program.
- CVE-2015-5600High
The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection. This allows remote attackers to conduct brute-force attacks or cause denial of service via a long and duplicative list in the ssh -oKbdInteractiveDevices option.
- CVE-2014-1692High
The hash_buffer function in schnorr.c in OpenSSH through 6.4, when Makefile.inc is modified to enable the J-PAKE protocol, does not initialize certain data structures. This may allow remote attackers to cause a denial of service (memory corruption) or have unspecified other impact via vectors that trigger an error condition.
- CVE-2026-110928Medium
A flaw was found in OpenSSH where the authorized_keys "restrict" keyword is not applied to tunnel forwarding. When PermitTunnel is enabled, a key restricted with "restrict" can still open a tunnel.
- CVE-2026-39832Critical
When adding a key to a remote agent, constraint extensions such as [email protected] were not serialized in the request. Destination restrictions were silently stripped when forwarding keys, allowing unrestricted use of the key on the remote host.
- CVE-2026-39831Critical
Vulnerability in the Verify() method for FIDO/U2F security keys ([email protected], [email protected]) – the User Presence flag was not checked. Signatures generated without physical touch were accepted, allowing unauthorized use of the key.
- CVE-2025-26466Medium
A flaw in the OpenSSH package causes each received ping packet to allocate a pong packet in memory, stored in a queue until key exchange completes. A malicious client can send such packets continuously, leading to uncontrolled memory consumption on the server.
- CVE-2025-26465Medium
A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is enabled. A machine-in-the-middle attack can be performed by a malicious machine impersonating a legit server. This issue occurs due to how OpenSSH mishandles error codes in specific conditions when verifying the host key.
- CVE-2023-51385Medium
In ssh in OpenSSH before 9.6, OS command injection might occur if a user name or host name has shell metacharacters, and this name is referenced by an expansion token in certain situations. For example, an untrusted Git repository can have a submodule with shell metacharacters in a user name or host name.
Original NVD description (English source)
sshd in OpenSSH before 10.6p2 on Linux, when musl libc is used without PAM, lacks a workaround for a password authentication bypass (related to misinterpretation of whether a string is intended to be a password hash). For some configurations of accounts, any password between 256 and 1024 characters succeeds. An example of a platform using musl libc without PAM is Alpine Linux.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS