CVE-2026-94029 Apache MINA SSHD: Memory exhaustion in SFTP v6 check-file-name/check-file-handle extension
Attacker can exhaust server memory via SFTP v6 extension requests, causing denial of service in Apache MINA SSHD.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-94029?
CVE-2026-94029 is a medium-severity denial of service vulnerability in Apache MINA SSHD, published on 30 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-770
Which versions are affected by CVE-2026-94029?
How do I fix CVE-2026-94029?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-94029 being exploited?
There is no known exploitation of CVE-2026-94029 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-94029, GHSA-fj5v-qh2p-6v8f, UBUNTU-CVE-2026-94029.