What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-09-27 · updated 2026-06-17
• Weakness: CWE-287

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.

Affected products

• jumpserver: before 3.5.6; from 3.6.0 before 3.6.5 — fixed in 3.5.6, 3.6.5

How to fix

Upgrade to a fixed version: jumpserver 3.5.6, 3.6.5. Check the vendor advisory for mitigations.

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
• https://github.com/jumpserver/jumpserver/security/advisories/GHSA-jv3c-27cv-w8jv

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