CVE-2021-43557 : Vulnerability Insights and Analysis
Learn about CVE-2021-43557 affecting Apache APISIX, allowing path traversal via the $request_uri variable. Immediate update to version 2.10.2 or code fix is necessary for mitigation.
Apache APISIX before 2.10.2 is affected by a path traversal vulnerability in the $request_uri variable, potentially allowing an attacker to bypass block lists. Immediate updates or code fixes are necessary to address this issue.
Understanding CVE-2021-43557
This CVE relates to a security vulnerability in Apache APISIX that can be exploited to bypass block lists using a specific URI construction.
What is CVE-2021-43557?
The uri-block plugin in Apache APISIX before version 2.10.2 utilizes the $request_uri variable without proper verification. This can enable the construction of URIs to circumvent blocklists, posing a security risk.
The Impact of CVE-2021-43557
The vulnerability allows attackers to bypass block lists in certain scenarios by manipulating the $request_uri variable. This issue can potentially expose systems to unauthorized access or other security threats.
Technical Details of CVE-2021-43557
This section covers the specific technical aspects of the CVE.
Vulnerability Description
The uri-block plugin in Apache APISIX before version 2.10.2 fails to verify the $request_uri variable, enabling the creation of URIs that evade block lists.
Affected Systems and Versions
- Product: Apache APISIX
- Vendor: Apache Software Foundation
- Versions Affected: Apache APISIX 1.5*
Exploitation Mechanism
Attackers can exploit this vulnerability by crafting URIs with specific patterns to evade block list restrictions, potentially gaining unauthorized access.
Mitigation and Prevention
To address CVE-2021-43557, immediate actions and long-term security practices are recommended.
Immediate Steps to Take
- Upgrade to Apache APISIX version 2.10.2
- Apply the provided commit to normalize the $request_uri: Commit Link
- Review and fix any custom code misusing the $request_uri variable.
Long-Term Security Practices
- Regularly update Apache APISIX to the latest versions
- Conduct security audits to identify and address similar vulnerabilities promptly
Patching and Updates
Stay informed about security patches and updates for Apache APISIX to minimize the risk of similar vulnerabilities being exploited.