CVE-2021-29441
CriticalExploitedIn 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.
Published Apr 27, 2021 · Updated Jul 9, 2026 · Also known as GHSA-36hp-jr8h-556f
Key Facts
Patch immediately- CVE-2021-29441 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Nacos (Alibaba), com.alibaba.nacos:nacos-common (maven).
- It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Oct 14, 2023 and is known to be used in ransomware campaigns. No public exploit code is known.
- EPSS estimates a 83% probability of exploitation in the next 30 days.
- Fixed versions are available, including Nacos 1.4.1, com.alibaba.nacos:nacos-common 1.4.1.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
83%
Higher than 99.6% of all scored CVEs
Exploited in the wild
Yes
2 catalog listings, used by ransomware
Public exploit code
None known
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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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Dec 1, 2023 | n/a | Known |
| CIRCL KEV | Oct 14, 2023 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| NacosAlibaba | >= < 1.4.1 | 1.4.1 |
| com.alibaba.nacos:nacos-commonmaven | See advisory | 1.4.1 |
Patched Releases
Nacos
1.4.1
com.alibaba.nacos:nacos-common
1.4.1
Timeline
Publicly disclosed
Apr 27, 2021
Added to CIRCL KEV
Oct 14, 2023
Added to Industry KEV feed
Dec 1, 2023
Last updated
Jul 9, 2026
Weakness Type
- CWE-290 Authentication Bypass by Spoofing
- CWE-306 Missing Authentication for Critical Function
References
- advisoryGHSA advisory
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2021-29441
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2021-29442
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
Nacos is a platform designed for dynamic service discovery and configuration and service management.
Affected: Nacos (Alibaba) versions >= < 1.4.1; com.alibaba.nacos:nacos-common (maven). The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Oct 14, 2023 and is known to be used in ransomware campaigns.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Nacos 1.4.1, com.alibaba.nacos:nacos-common 1.4.1.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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