# 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.

- **Severity:** Medium 6.9 (`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`)
- **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 available:** No
- **Published:** 13 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-ch3q-cw5r-f4hg

## 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.

Weakness: CWE-789 (Memory Allocation with Excessive Size Value), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-54700?

2 open source packages ship an affected version, including org.connectbot.sshlib:sshlib.


| Package | Ecosystem | 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.

## Is CVE-2026-54700 being exploited?

There is no known exploitation of CVE-2026-54700 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54700 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-54700 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.connectbot.sshlib:sshlib (Maven): affected all versions up to 0.3.0; no fix listed
- org.connectbot.sshlib:sshlib (Maven): affected all versions up to 0.3.0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54700/ (Markdown: https://insights.sbomify.com/CVE-2026-54700/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54700
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54700
- OSV: https://osv.dev/vulnerability/CVE-2026-54700

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54700/
Summaries are generated and may contain mistakes; the official description above is the record.