dbcve.org
Sing BoxApplication · Sagernet

CVE-2023-43644

CRITICAL · 9.8 CVSS v3.1 Published 2023-09-25
Fix available
A fix is available. Upgrade to 1.4.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Sing-box is an open source proxy system. Affected versions are subject to an authentication bypass when specially crafted requests are sent to sing-box. This affects all SOCKS5 inbounds with user authentication and an attacker may be able to bypass authentication. Users are advised to update to sing-box 1.4.4 or to 1.5.0-rc.4. Users unable to update should not expose the SOCKS5 inbound to insecure environments.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Sing-box proxy system versions prior to 1.4.4 and 1.5.0-rc.4 contain an authentication bypass vulnerability in SOCKS5 inbounds. Attackers can send specially crafted requests to bypass user authentication and gain unauthorized proxy access.

MitigationUpdate sing-box to version 1.4.4 or 1.5.0-rc.4. If immediate updating is not possible, ensure SOCKS5 inbounds are not exposed to untrusted networks.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Sing BoxApplication
Affected:< 1.4.5= 1.5.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check sing-box installed version
    Run `sing-box version` or check your package manager for the installed sing-box package version
    Affected if Version is below 1.4.5 or equals 1.5.0 exactly (1.5.0-rc.4 and later are fixed)
  2. Locate sing-box configuration file
    Common locations: /etc/sing-box/config.json, ~/.sing-box/config.json, or the path specified via `sing-box run -C <path>`
    Affected if Configuration file exists and contains SOCKS5 inbound definitions
  3. Verify SOCKS5 inbound is configured
    Open the configuration file and search for inbounds with "type": "socks"
    Affected if A SOCKS5 inbound (type "socks") is defined in the configuration
  4. Check SOCKS5 inbound exposure
    In the SOCKS5 inbound config, inspect the "listen" field. Check if it binds to 0.0.0.0, ::, or a public IP address rather than 127.0.0.1 or localhost
    Affected if The SOCKS5 inbound listen address is set to 0.0.0.0, ::, or any public IP, making it network-accessible

You are affected if sing-box version is < 1.4.5 or exactly 1.5.0 AND a SOCKS5 inbound is enabled and bound to a network-accessible address.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.4.5 or later
Fixed in 1.4.5
Interim mitigation

Update sing-box to version 1.4.4 or 1.5.0-rc.4. If immediate updating is not possible, ensure SOCKS5 inbounds are not exposed to untrusted networks.

Recommended fix High confidence

sing-box 1.5.0-rc.4 (or subsequent stable release)

  1. 1. Identify the current sing-box version by running 'sing-box version' or checking your package manager.
  2. 2. If running a version < 1.4.5 or exactly 1.5.0, plan for upgrade.
  3. 3. Download the fixed release: sing-box 1.5.0-rc.4 (recommended stable fix) from the official GitHub releases at github.com/SagerNet/sing-box.
  4. 4. Stop the sing-box service before upgrading (e.g., 'systemctl stop sing-box' or equivalent).
  5. 5. Install the new version using your package manager or manual binary replacement.
  6. 6. Verify the new version is installed by running 'sing-box version'.
  7. 7. Restart the sing-box service (e.g., 'systemctl start sing-box').
  8. 8. If upgrade is not possible, ensure SOCKS5 inbounds are not exposed to untrusted networks; bind only to localhost or trusted internal IPs, or disable the SOCKS5 inbound entirely.
Caveat Review release notes for any configuration changes between your current version and 1.5.0-rc.4; SOCKS5 authentication behavior may have changed.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Sing Box Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,770
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-43644 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data