What is the CVSS score of CVE-2021-43557?

CVE-2021-43557 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. EPSS exploitation probability: 14.6%.

Is there a public PoC exploit available for CVE-2021-43557?

Yes, a public proof-of-concept exploit is available for CVE-2021-43557. Prioritise patching immediately. EPSS: 14.6%.

Apisix CVE-2021-43557

HIGH

Command Injection (CWE-77)

2021-11-22 security@apache.org

Apache Command Injection Apisix

7.5

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Lifecycle Timeline

CVE Published

Nov 22, 2021 - 09:15 nvd

HIGH 7.5

DescriptionNVD

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.

AnalysisAI

The uri-block plugin in Apache APISIX before 2.10.2 uses $request_uri without verification. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Technical ContextAI

This vulnerability is classified as Command Injection (CWE-77), which allows attackers to inject arbitrary commands into system command execution. 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. Affected products include: Apache Apisix. Version information: before 2.10.2.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Use parameterized APIs, avoid shell execution, validate input with strict allowlists.