CVE-2026-54700 ConnectBot SSH: Unbounded SSH field lengths can cause excessive memory allocation
A malicious SSH server can cause the ConnectBot SSH client library to crash via excessive memory allocation triggered by malformed packet fields.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-54700?
CVE-2026-54700 is a medium-severity denial of service vulnerability in connectbot cbssh, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
ConnectBot SSH Client Library is written in Kotlin with Kaitai Struct and KStateMachine. Prior to 0.3.1, the SSH protocol parser trusts attacker-controlled inner byte lengths and element counts without verifying that they fit in the containing packet. A malicious or compromised SSH server can return a small malformed packet whose oversized declarations cause the Kaitai Struct Java runtime to attempt excessive allocation or repeated parsing before detecting truncated input. The general transport path requires a client connection but no authentication or optional feature; malformed SSH-agent messages additionally require SSH agent forwarding. The issue can raise an uncaught OutOfMemoryError and terminate the application process, with no demonstrated confidentiality or integrity impact. This issue is fixed in version 0.3.1.
Which versions are affected by CVE-2026-54700?
2 open source packages ship an affected version, including org.connectbot.sshlib:sshlib.
| Package | Affected | Fixed in |
|---|---|---|
org.connectbot.sshlib:sshlib Maven | All versions to 0.3.0 | None |
org.connectbot.sshlib:sshlib Maven | All versions to 0.3.0 | None |
How do I fix CVE-2026-54700?
No fix has been published for CVE-2026-54700 yet. Limit exposure of the affected software until one is available.
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-2026-54700 being exploited?
There is no known exploitation of CVE-2026-54700 in the wild and no public exploit code.
Sources
Also known as GHSA-ch3q-cw5r-f4hg.