# CVE-2021-29441 — alibaba nacos

> As of 2024-08-03, CVE-2021-29441 is a HIGH-severity vulnerability in alibaba nacos, CVSS v3.1 8.6, EPSS 83.4% (99.6th percentile). Threadlinqs Intelligence links 9 tracked threat campaigns to CVE-2021-29441, most recently “AI-accelerated intrusions: Microsoft 2026 Digital Defense Report on phishing, public-facing app exploitation, and AI-enabled attacker tooling (s1ngularity, PromptLock, JADEPUFFER/ENCFORGE)”.

**Last updated:** 2024-08-03

## What is CVE-2021-29441?

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.

The record classifies CVE-2021-29441 under weakness class [CWE-290](https://intel.threadlinqs.com/cwe/CWE-290). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 1987 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.6 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N`)
- **EPSS (FIRST):** 83.4% probability of exploitation in the next 30 days, higher than 99.6% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 10/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2021-04-27, last modified 2024-08-03

## Is CVE-2021-29441 being exploited?

Weaponised exploit code for CVE-2021-29441 is publicly available. 4 public proof-of-concept repositories are tracked for this identifier. A ProjectDiscovery Nuclei detection template exists (`http/cves/2021/CVE-2021-29441.yaml`).

- [bysinks/CVE-2021-29441](https://github.com/bysinks/CVE-2021-29441) (github)
- [hh-hunter/nacos-cve-2021-29441](https://github.com/hh-hunter/nacos-cve-2021-29441) (github)
- [azhao1981/CVE-2021-29441](https://github.com/azhao1981/CVE-2021-29441) (github)
- [trickest/cve](https://github.com/trickest/cve/blob/main/2021/CVE-2021-29441.md) (trickest)

## Affected products and versions

- **alibaba**: nacos

Affected software packages:

- `maven:com.alibaba.nacos:nacos-common` — patched in 1.4.1

## How to fix CVE-2021-29441

The record marks a vendor fix as available for CVE-2021-29441. Fixed versions are recorded for 1 package: maven:com.alibaba.nacos:nacos-common 1.4.1. Patch reference: [https://github.com/alibaba/nacos/pull/4703](https://github.com/alibaba/nacos/pull/4703). Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

## Threat activity tracking CVE-2021-29441

9 tracked threats in the Threadlinqs corpus reference CVE-2021-29441, either in the campaign’s CVE list or as an indicator on the campaign record.

- [AI-accelerated intrusions: Microsoft 2026 Digital Defense Report on phishing, public-facing app exploitation, and AI-enabled attacker tooling (s1ngularity, PromptLock, JADEPUFFER/ENCFORGE)](https://intel.threadlinqs.com/threat/TL-2026-2880) — HIGH · 2026-10-03
- [Chinese-Speaking Operator "Nie" Uses SecFlow AI Orchestration Framework (Claude, Qwen, DeepSeek) and GLUTTON Steganographic Webshell in Multi-Country Espionage Campaign](https://intel.threadlinqs.com/threat/TL-2026-2325) — HIGH · 2026-09-04
- [Chinese-speaking threat group UAT-10147 uses agentic AI to automate exploitation of internet-facing web servers](https://intel.threadlinqs.com/threat/TL-2026-2096) — HIGH · 2026-08-21
- [WP-SHELLSTORM: Exposed Chinese-Speaking Threat Actor Server Reveals Mass WordPress/Joomla Webshell Brokerage Targeting 1.4M Domains via CVE-2026-48907 (Joomla JCE) and CVE-2021-29441 (Nacos)](https://intel.threadlinqs.com/threat/TL-2026-1180) — HIGH · 2026-07-10
- [JADEPUFFER: AI Agent Exploits Langflow RCE (CVE-2025-3248) to Automate Database Ransomware/Extortion Attack](https://intel.threadlinqs.com/threat/TL-2026-1117) — CRITICAL · 2026-07-05
- [JADEPUFFER Agentic Ransomware: Autonomous LLM Agent Exploits Langflow (CVE-2025-3248) and Nacos (CVE-2021-29441) for End-to-End Database Extortion](https://intel.threadlinqs.com/threat/TL-2026-1102) — CRITICAL · 2026-07-04
- [JADEPUFFER: First End-to-End Agentic Ransomware Attack Exploiting Langflow (CVE-2025-3248) and Nacos (CVE-2021-29441)](https://intel.threadlinqs.com/threat/TL-2026-1083) — CRITICAL · 2026-07-02
- [JADEPUFFER Agentic Ransomware Exploits Langflow CVE-2025-3248 and Nacos CVE-2021-29441 via Base64-Encoded Python Payloads](https://intel.threadlinqs.com/threat/TL-2026-1116) — CRITICAL · 2026-07-02
- [JADEPUFFER: Agentic (LLM-Driven) Ransomware Automating Database Extortion via Langflow RCE (CVE-2025-3248) and Nacos Auth Bypass (CVE-2021-29441)](https://intel.threadlinqs.com/threat/TL-2026-1044) — CRITICAL · 2026-07-01

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories, ProjectDiscovery Nuclei. Last verified by Threadlinqs on 2026-10-05. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com](https://github.com/advisories/GHSA-36hp-jr8h-556f)

**Other references**

- [github.com](https://github.com/alibaba/nacos/issues/4701)
- [github.com (4703)](https://github.com/alibaba/nacos/pull/4703)

Canonical: https://intel.threadlinqs.com/cve/CVE-2021-29441
Full detection coverage and IOCs for threats exploiting CVE-2021-29441 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp