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. 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 (github)
- hh-hunter/nacos-cve-2021-29441 (github)
- azhao1981/CVE-2021-29441 (github)
- trickest/cve (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. 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) — 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 — HIGH · 2026-09-04
- Chinese-speaking threat group UAT-10147 uses agentic AI to automate exploitation of internet-facing web servers — 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) — HIGH · 2026-07-10
- JADEPUFFER: AI Agent Exploits Langflow RCE (CVE-2025-3248) to Automate Database Ransomware/Extortion Attack — 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 — CRITICAL · 2026-07-04
- JADEPUFFER: First End-to-End Agentic Ransomware Attack Exploiting Langflow (CVE-2025-3248) and Nacos (CVE-2021-29441) — CRITICAL · 2026-07-02
- JADEPUFFER Agentic Ransomware Exploits Langflow CVE-2025-3248 and Nacos CVE-2021-29441 via Base64-Encoded Python Payloads — 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) — 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 . This product uses the NVD API but is not endorsed or certified by the NVD.