CVE-2026-94029: Apache MINA SSHD: Memory exhaustion in SFTP v6 check-file-name/check-file-handle extension

Severity: medium (CVSS 6.5 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-770

Description

Server-side memory exhaustion in Apache MINA SSHD 1.0.0 to 2.19.0 and 3.0.0-M1 to 3.0.0-M5, component sshd-sftp, in the SFTP v6 check-file-name/check-file-handle extension. Apache MINA SSHD is a Java library for client-side and server-side SSH. Using a very small "block size" (for instance 256, which is the minimum) on a huge file generates many (file size / block size) hashes. The resulting SFTP reply message was accumulated fully in memory server-side, which could, with a suitably large (possibly sparse) file exhaust the server-side memory, taking down the server. Users are recommended to upgrade to version 2.20.0 or 3.0.0-M6, which fix this issue by imposing a maximum limit on the size of the reply. Many SFTP implementations have a general limit on the size of SFTP messages anyway; typically 256kB as in OpenSSH or also in Apache MINA SSHD.

Affected products

Apache Software Foundation Apache MINA SSHD: from 1.0.0 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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