Auth bypass in Charm Soft Serve

CVE-2023-43809

Soft Serve is a self-hostable Git server for the command line. Prior to version 0.6.2, 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. Users should upgrade to the latest Soft Serve version `v0.6.2` to receive the patch for this issue. To workaround this vulnerability without upgrading, users can temporarily disable Keyboard-Interactive SSH Authentication using the `allow-keyless` setting.

Vulnerability class: Broken Authentication

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.012 (68.4th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 68.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2023-43809: held from 0.009 to 0.012.

EPSS over last 30 days · oldest: 0.009 · newest: 0.012 · change: +0.003

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2023-43809?
CVE-2023-43809 is a high-severity vulnerability in Charm Soft Serve, classified under Improper Authentication. CVSS score: 7.5/10. Published 2023-10-04.
How severe is CVE-2023-43809?
High severity. CVSS v3 base score is 7.5 out of 10.