CVE-2023-43809Public exploitNetwork attack vector

Unauthenticated SSH access via public-key mismatch

Published Oct 4, 2023 · Updated Sep 20, 2024

Improper authentication in Charmbracelet Soft Serve before 0.6.2 allows remote attackers to gain unauthorized SSH access. The SSH handshake records a user when a public key is offered but does not verify that the same key completes authentication before keyboard-interactive access is accepted. Exposure requires allow-keyless keyboard-interactive authentication and a key that needs additional client-side verification, such as FIDO2 or GPG.

CVSS severity7.5
High
EPSS probability0.89%
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 Charmbracelet Soft Serve before 0.6.2 allows remote attackers to gain unauthorized SSH access. The SSH handshake records a user when a public key is offered but does not verify that the same key completes authentication before keyboard-interactive access is accepted. Exposure requires allow-keyless keyboard-interactive authentication and a key that needs additional client-side verification, such as FIDO2 or GPG.

The record

CVE
CVE-2023-43809
Published
Oct 4, 2023
Updated
Sep 20, 2024
Vendor
Charmbracelet
Product
Soft Serve
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 20, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=0 <0.6.2
  2. Affected versionversion=< 0.6.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Charmbracelet · Soft Serveversion=0 <0.6.2; version=< 0.6.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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.

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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-287Improper Authentication
T1190Exploit Public-Facing Application

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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