CVE-2023-43644 is a critical-severity (CVSS 9.1) Missing Authentication vulnerability in github.com/sagernet/sing-box. A fix is available for github.com/sagernet/sing-box — see the affected versions and patch details below.
Improper authentication in the SOCKS5 inbound in sing-box
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-43644.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-43644 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/sagernet/sing-box🐹github.com/sagernet/sing-box🐹github.com/sagernet/singReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/sagernet/sing-box | all versions | 1.4.5go get github.com/sagernet/sing-box@v1.4.5 |
| 🐹Go | github.com/sagernet/sing-box | ≥ 1.5.0-beta.1&&< 1.5.0-rc.5 | 1.5.0-rc.5go get github.com/sagernet/sing-box@v1.5.0-rc.5 |
| 🐹Go | github.com/sagernet/sing | all versions | 0.2.12-0.20230925092853-5b05b5c147d9go get github.com/sagernet/sing@v0.2.12-0.20230925092853-5b05b5c147d9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sagernet/sing-box, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/sagernet/sing-box to 1.4.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-43644 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-43644 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-43644. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-43644 in your dependencies?
O3 Security finds CVE-2023-43644 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.