What’s Vulnerable › Vulnerabilities

CVE-2026-54700: ConnectBot SSH: Unbounded SSH field lengths can cause excessive memory allocation

• Severity: medium (CVSS 6.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-13 · updated 2026-10-16
• Weakness: CWE-20

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.

Affected products

• connectbot cbssh: before 0.3.1

References

• https://github.com/connectbot/cbssh/commit/a08421fbe7cf8b72fa60fb8b2f98fb465dc43fd9
• https://github.com/connectbot/cbssh/pull/194
• https://github.com/connectbot/cbssh/releases/tag/v0.3.1
• https://github.com/connectbot/cbssh/security/advisories/GHSA-ch3q-cw5r-f4hg

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