Description
Nacos is a platform designed for dynamic service discovery and configuration and service management. In Nacos before version 1.4.1, when configured to use authentication (-Dnacos.core.auth.enabled=true) Nacos uses the AuthFilter servlet filter to enforce authentication. This filter has a backdoor that enables Nacos servers to bypass this filter and therefore skip authentication checks. This mechanism relies on the user-agent HTTP header so it can be easily spoofed. This issue may allow any user to carry out any administrative tasks on the Nacos server.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| alibaba | nacos | < 1.4.1 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 4 repositories
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bysinks/CVE-2021-29441 ★ 2 · Mar 15, 2022
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CyberCTF/vulhub-nacos-cve-2021-29441 ★ 0 · Oct 8, 2026
Vulhub nacos/CVE-2021-29441: Nacos User-Agent Authentication Bypass (CVE-2021-29441), run with Isoloom
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azhao1981/CVE-2021-29441 ★ 0 · Dec 4, 2024
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hh-hunter/nacos-cve-2021-29441 ★ 0 · Oct 5, 2021
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Automated scanner template
A ready-made Nuclei template detects this vulnerability automatically. Vulnerabilities with public scanner templates are typically probed across the internet soon after the template appears — exposed systems should be patched first.
- Nacos <1.4.1 - Authentication Bypass http/cves/2021/CVE-2021-29441.yaml
Source: projectdiscovery/nuclei-templates (MIT) — updated daily. Only links are listed.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Maven | com.alibaba.nacos:nacos-common | < 1.4.1 | 1.4.1 | GHSA-36hp-jr8h-556f |