CVE-2021-43557

Path traversal in request_uri variable

HIGH
7.5
CVSS Score
Published: November 22, 2021 at 08:25 AM UTC
Updated: June 17, 2026 at 04:11 AM UTC
1 product affected across 1 vendorApisix

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Severity
HIGH7.5
Exploit prediction
EPSS 13%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.10.21.5 ≤ v < Apache APISIX 1.5*1.5
Affected range stops below 2.10.2, so it looks safe — our inference, not a vendor statement
Affected range stops below Apache APISIX 1.5*, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

Mailing Listx_refsource_MLISTThird Party Advisory
http://www.openwall.com/lists/oss-security/2021/11/22/1
Mailing Listx_refsource_MLISTThird Party Advisory
http://www.openwall.com/lists/oss-security/2021/11/22/2
Mailing Listx_refsource_MLISTExploitThird Party Advisory
http://www.openwall.com/lists/oss-security/2021/11/23/1
x_refsource_MISCExploitMailing ListVendor Advisory
https://lists.apache.org/thread/18jyd458ptocr31rnkjs71w4h366mv7h

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-77

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