CVE-2026-93994: Apache MINA SSHD: Repeated-publickey policy bypass on server

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-30 · updated 2026-09-30
Weakness: CWE-304

Description

Apache MINA SSHD is a Java library for client-side and server-side SSH. SSH servers can be configured to require multi-authentication schemes, for instance two different public keys, not just one. In OpenSSH, this would be done by setting in sshd_config AuthenticationMethods "publickey,publickey". Apache MINA SSHD provides an equivalent configuration mechanism. In Apache MINA SSHD versions up to 2.19.0 and 3.0.0-M1 to 3.0.0-M5 the server code in component sshd-core does not enforce that the two public keys presented are different. A user can thus successfully authenticate with only one of the two key pairs required by presenting this single key twice. This is a partial authentication bypass. Users are recommended to upgrade to version 2.20.0 or 3.0.0-M6, which fix this issue.

Affected products

Apache Software Foundation Apache MINA SSHD: before 2.20.0; from 3.0.0-M1 before 3.0.0-M6 — fixed in 2.20.0, 3.0.0-M6

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache MINA SSHD 2.20.0, 3.0.0-M6. Check the vendor advisory for mitigations.

References

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