AI analysis
Apache MINA SSHD, a Java library used to build SSH clients and servers, contains a logic error in its rarely used server-side 'asynchronous authentication' feature that can skip signature verification or return a wrong result during public-key or hostbased authentication. An unauthenticated attacker with network access to a vulnerable SSH server could potentially complete authentication without a valid key, gaining the account access that key would have provided (high confidentiality and integrity impact, CVSS 9.1). Only applications whose developers explicitly wrote code to use asynchronous authentication are affected; standard deployments of the library that do not invoke this mechanism are not on the vulnerable path. Maintainers of Java products embedding MINA SSHD 2.0.0–2.19.0 or 3.0.0-M1–3.0.0-M5 should audit for that code pattern and upgrade to 2.20.0 or 3.0.0-M6. No public proof-of-concept exists, no exploitation in the wild has been reported, and the CVE is not on CISA's KEV list.
What to do: Upgrade the embedded Apache MINA SSHD library to 2.20.0 (2.x line) or 3.0.0-M6 (3.x line). If you ship or operate a product built on MINA SSHD, audit whether your server code explicitly enables asynchronous authentication — if it does not, you are not on the vulnerable path, though upgrading is still recommended. Note that the fix now closes SSH sessions that combine asynchronous authentication with public-key or hostbased schemes (logging that async auth is allowed only with password or keyboard-interactive), so test any custom authentication flows after upgrading.
Affected
| Apache MINA SSHD | 2.0.0 to 2.19.0 |
| Apache MINA SSHD | 3.0.0-M1 to 3.0.0-M5 |
Estimated exposure
—No basis for an estimate.
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description
Authentication bypass in sshd-core in Apache MINA SSHD versions 2.0.0 to 2.19.0 and 3.0.0-M1 to 3.0.0-M5 for a certain (presumed rare) way to implement an SSH server. Apache MINA SSHD is a Java library for client- and server-side SSH. In the server part of the library, a mechanism to perform "asynchronous authentication" exists. A server implemented with Apache MINA SSHD must contain explicit code to make use of this feature. The implementation of this feature was flawed and could potentially lead to skipping checking the signature in public-key or hostbased authentication, or returning a wrong result. Users are recommended to upgrade to Apache MINA SSHD 2.20.0 or 3.0.0-M6, which fix the logic error and which additionally forbid the use of this "asynchronous authentication" mechanism with the public-key or hostbased authentication schemes: if used, the SSH session will be closed and the server will log an entry indicating that asynchronous authentication may be used only with password or keyboard-interactive authentication.