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CVE-2021-43557

7.5 · HIGH

The uri-block plugin in Apache APISIX before 2.10.2 uses $request_uri without verification.

Published Nov 22, 2021CWE-77EPSS 12.94%

Overview

CVE-2021-43557 is a high-severity vulnerability. It was published on November 22, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

The uri-block plugin in Apache APISIX before 2.10.2 uses $request_uri without verification. The $request_uri is the full original request URI without normalization. This makes it possible to construct a URI to bypass the block list on some occasions. For instance, when the block list contains "^/internal/", a URI like `//internal/` can be used to bypass it. Some other plugins also have the same issue. And it may affect the developer's custom plugin.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refwww.openwall.com/lists/oss-security/2021/11/22/1Refwww.openwall.com/lists/oss-security/2021/11/22/2Refwww.openwall.com/lists/oss-security/2021/11/23/1Reflists.apache.org/thread/18jyd458ptocr31rnkjs71w4h366mv7hRefwww.openwall.com/lists/oss-security/2021/11/22/1Refwww.openwall.com/lists/oss-security/2021/11/22/2Refwww.openwall.com/lists/oss-security/2021/11/23/1Reflists.apache.org/thread/18jyd458ptocr31rnkjs71w4h366mv7h

How CyberStrike helps

Frequently asked questions

What is CVE-2021-43557?

CVE-2021-43557 is a high-severity vulnerability. It was published on November 22, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2021-43557?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-43557?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-43557?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-43557 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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