CVE-2023-43644Network attack vector

Unauthenticated proxy access via unchecked SOCKS authentication

Published Sep 25, 2023 · Updated Sep 24, 2024

Authentication bypass in SagerNet sing-box before 1.4.5 allows remote attackers to use authenticated SOCKS inbounds without valid credentials. The SOCKS handshake path continued to read a proxy request after a failed username/password response, while the inbound also accepted SOCKS4 requests that cannot carry those credentials. Exposure requires a network-reachable SOCKS inbound with users configured and grants unauthorized use of the proxy routes permitted by that inbound.

CVSS severity9.1
Critical
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in SagerNet sing-box before 1.4.5 allows remote attackers to use authenticated SOCKS inbounds without valid credentials. The SOCKS handshake path continued to read a proxy request after a failed username/password response, while the inbound also accepted SOCKS4 requests that cannot carry those credentials. Exposure requires a network-reachable SOCKS inbound with users configured and grants unauthorized use of the proxy routes permitted by that inbound.

The record

CVE
CVE-2023-43644
Published
Sep 25, 2023
Updated
Sep 24, 2024
Vendor
SagerNet
Product
sing-box
Classifications
CWE-306, T1090
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 25, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 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 <1.5.0-rc.5
  2. Affected versionversion=< 1.4.5
  3. Affected versionversion=>= 1.5.0-beta.1, < 1.5.0-rc.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SagerNet · sing-boxversion=0 <1.5.0-rc.5; version=< 1.4.5; version=>= 1.5.0-beta.1, < 1.5.0-rc.4

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.1GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1090Proxy

Public exploit references

No public exploit references are available in this record.

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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