CVE-2026-54700 PUBLISHED

ConnectBot SSH: Unbounded SSH field lengths can cause excessive memory allocation

Assigner: GitHub_M
Reserved: 15.06.2026 Published: 13.10.2026 Updated: 13.10.2026

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.

Metrics

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS Score: 6.9

Product Status

Vendor connectbot
Product cbssh
Versions
  • Version < 0.3.1 is affected

References

Problem Types

  • CWE-20: Improper Input Validation CWE
  • CWE-789: Memory Allocation with Excessive Size Value CWE