CVE-2021-43557
Path traversal in request_uri variable
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2021-43557- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-77
- Updated
- 2026-11-02
CVE List No score
Path traversal in request_uri variable
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.
- Record
CVE-2021-43557- Updated
- 2026-11-02
EUVDEUVD-2021-30486 No score
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.
- Record
EUVD-2021-30486- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-9wxc-375c-cvq2 No score
The uri-block plugin in Apache APISIX before 2.10.2 uses $request_uri without verification. The ...
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.
- Record
GHSA-9wxc-375c-cvq2- Weakness
- CWE-77
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-43557- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVBIT-apisix-2021-43557 No score
Path traversal in request_uri variable
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.
- Record
BIT-apisix-2021-43557- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
apisixBitnami |
before 2.10.2 | 2.10.2 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | xvnpw/k8s-CVE-2021-43557-poc | 2021-11-22 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-43557 is a high vulnerability (CVSS 7.5) in Apache Apisix, published November 22, 2021. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 13.0%, the 96th percentile. Fixed in apisix 2.10.2.