oss-security - CVE-2021-43557: Apache APISIX: Path traversal in request

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Date: Mon, 22 Nov 2021 14:30:19 +0800
From: Zexuan Luo <spacewander@...che.org>
To: announce@...che.org, dev@...six.apache.org, security@...che.org, 
	oss-security@...ts.openwall.com, niemiec.marcin@...il.com
Subject: CVE-2021-43557: Apache APISIX: Path traversal in request_uri variable

Severity: moderate

Description:

The uri-block plugin in APISIX 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.

This issue is fixed in APISIX 2.10.2.
Thanks to Marcin Niemiec for reporting the vulnerability.

Mitigation:

1. Upgrade to APISIX 2.10.2
2. Carefully review custom code, find & fix the usage of $request_uri
without verification.

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

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