CVE-2023-43644 | Improper authentication in the SOCKS5 inbound in sing-box

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.

Published: 2023-09-25 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-43644 is rated Moderate Risk (53.5/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.68%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-43644

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.17% 0.68% +0.51%
2 2025-11-21 0.34% 0.17% -0.17%
3 2025-11-18 — 0.34% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-43644

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.2 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2023-43644

GitHub Security Advisory for CVE-2023-43644

GHSA-r5hm-mp3j-285g · Severity: critical · Ecosystem: go — sing-box vulnerable to improper authentication in the SOCKS inbound

Affected software / configurations for CVE-2023-43644

Vendor Product Version Raw CPE
sagernet sing-box < 1.4.5 cpe:2.3:a:sagernet:sing-box:*:*:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta1:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta10:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta11:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta12:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta2:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta3:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta4:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta5:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta6:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta7:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta8:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:beta9:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:rc1:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:rc2:*:*:*:*:*:*
sagernet sing-box 1.5.0 cpe:2.3:a:sagernet:sing-box:1.5.0:rc3:*:*:*:*:*:*

References for CVE-2023-43644

cvelogic Threat Intelligence