CVE-2021-43557

Apisix vulnerability

CVSS

7.5

EPSS

14.6%

EPSS pct

96th

Exploited

No known

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 vendor

Apache

Affected product

Apisix

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Weakness type (CWE)

CWE-77 — Command Injection

Published

2021-11-22

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to confidentiality.

Its EPSS score of 14.6% reflects a moderate probability of exploitation activity in the wild over the next 30 days, placing it above 96% of all scored CVEs.

Check your external exposure to CVE-2021-43557

Confirm whether Apache Apisix is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2021-43557.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-43557

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