How severe is CVE-2021-29441?

CVE-2021-29441 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-29441 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 74% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-29441?

CVE-2021-29441 affects Alibaba Nacos. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-29441?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-29441 published?

CVE-2021-29441 was published on 2021-04-27 and last updated on 2026-06-17.

CVE-2021-29441

CVE-2021-29441 is a high-severity vulnerability in Alibaba Nacos with a CVSS 3.x base score of 8.6. Its EPSS exploit-prediction score of 74% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-290.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 7.5
EPSS exploit prediction: 74% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-290
Affected product: Alibaba Nacos
Published: 2021-04-27
Last modified: 2026-06-17

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.

Frequently asked questions

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.
How severe is CVE-2021-29441?: CVE-2021-29441 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-29441 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 74% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-29441?: CVE-2021-29441 affects Alibaba Nacos. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-29441?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-29441 published?: CVE-2021-29441 was published on 2021-04-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:alibaba:nacos:*:*:*:*:*:*:*:*

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