CVE-2023-42818Public exploitNetwork attack vector

MFA bypass via skipped SSH private-key proof

Published Sep 27, 2023 · Updated Mar 25, 2025

Improper authentication in JumpServer's Koko SSH server before 3.5.6 and 3.6.0 through 3.6.4 allows remote attackers to reach MFA. Koko treats presentation of a registered public key as partial SSH authentication without requiring proof of possession of the matching private key. The attacker needs a target username and disclosed registered public key, and exploitation then depends on completing or brute-forcing the user's MFA challenge.

CVSS severity5.4
Medium
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in JumpServer's Koko SSH server before 3.5.6 and 3.6.0 through 3.6.4 allows remote attackers to reach MFA. Koko treats presentation of a registered public key as partial SSH authentication without requiring proof of possession of the matching private key. The attacker needs a target username and disclosed registered public key, and exploitation then depends on completing or brute-forcing the user's MFA challenge.

The record

CVE
CVE-2023-42818
Published
Sep 27, 2023
Updated
Mar 25, 2025
Vendor
JumpServer
Product
JumpServer
Classifications
CWE-307, CWE-287, T1110
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 27, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 25, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.5.6
  2. Affected versionversion=< 3.5.6
  3. Affected versionversion=>= 3.6.0, < 3.6.5
  4. Affected versionversion=3.6.0 <3.6.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

JumpServer · JumpServerversion=0 <3.5.6; version=< 3.5.6; version=>= 3.6.0, < 3.6.5; version=3.6.0 <3.6.5

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
CWE-287Improper Authentication
T1110Brute Force

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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