CVE-2023-43809

Workarounds

To workaround this vulnerability without upgrading, users can temporarily disable Keyboard-Interactive SSH Authentication using the allow-keyless setting.

References

https://github.com/charmbracelet/soft-serve/issues/389

A security vulnerability in Soft Serve could allow an unauthenticated, remote attacker to bypass public key authentication when keyboard-interactive SSH authentication is active, through the allow-keyless setting, and the public key requires additional client-side verification for example using FIDO2 or GPG. This is due to insufficient validation procedures of the public key step during SSH request handshake, granting unauthorized access if the keyboard-interaction mode is utilized. An attacker could exploit this vulnerability by presenting manipulated SSH requests using keyboard-interactive authentication mode. This could potentially result in unauthorized access to the Soft Serve.

The application does not adequately verify the identity of a user, device, or process before granting access. Typical impact: unauthorized access to functions or data reserved for authenticated parties.

CVE-2023-43809 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.6.2); upgrading removes the vulnerable code path.

Kodem intelligence

Users should upgrade to the latest Soft Serve version v0.6.2 to receive the patch for this issue.

1. What is CVE-2023-43809? CVE-2023-43809 is a high-severity improper authentication vulnerability in github.com/charmbracelet/soft-serve (go), affecting versions < 0.6.2. It is fixed in 0.6.2. The application does not adequately verify the identity of a user, device, or process before granting access.
2. How severe is CVE-2023-43809? CVE-2023-43809 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/charmbracelet/soft-serve are affected by CVE-2023-43809? github.com/charmbracelet/soft-serve (go) versions < 0.6.2 is affected.
4. Is there a fix for CVE-2023-43809? Yes. CVE-2023-43809 is fixed in 0.6.2. Upgrade to this version or later.
5. Is CVE-2023-43809 exploitable, and should I be worried? Whether CVE-2023-43809 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-43809 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-43809? Upgrade github.com/charmbracelet/soft-serve to 0.6.2 or later.