CVE-2021-43116
HIGHCVE-2021-43116 is a high-severity (CVSS 8.8) Improper Authentication vulnerability in com.alibaba.nacos:nacos-client. 3 public exploit references exist, so weaponization risk is real. O3 Security confirms whether CVE-2021-43116 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Use of Hard-coded Credentials in Nacos
Blast Radius
com.alibaba.nacos:nacos-clientReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
An Access Control vulnerability exists in Nacos 2.0.3 in the access prompt page; enter username and password, click on login to capture packets and then change the returned package, which lets a malicious user login.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.alibaba.nacos:nacos-client | all versions | No fix |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Nacos 2.0.3 - Access Control vulnerability
by Jenson Zhao · Apr 3, 2023
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.alibaba.nacos:nacos-client. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of com.alibaba.nacos:nacos-client has shipped for CVE-2021-43116 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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 pinpoints whether CVE-2021-43116 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-43116. 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-2021-43116 in your dependencies?
O3 detects CVE-2021-43116 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.