CVE-2021-29492

Envoy is a cloud-native edge/middle/service proxy. Envoy does not decode escaped slash sequences `%2F` and `%5C` in HTTP URL paths in versions 1.18.2 and before. A remote attacker may craft a path with escaped slashes, e.g. `/something%2F..%2Fadmin`, to bypass access control, e.g. a block on `/admin`. A backend server could then decode slash sequences and normalize path and provide an attacker access beyond the scope provided for by the access control policy. ### Impact Escalation of Privileges when using RBAC or JWT filters with enforcement based on URL path. Users with back end servers that interpret `%2F` and `/` and `%5C` and `\` interchangeably are impacted. ### Attack Vector URL paths containing escaped slash characters delivered by untrusted client. Patches in versions 1.18.3, 1.17.3, 1.16.4, 1.15.5 contain new path normalization option to decode escaped slash characters. As a workaround, if back end servers treat `%2F` and `/` and `%5C` and `\` interchangeably and a URL path based access control is configured, one may reconfigure the back end server to not treat `%2F` and `/` and `%5C` and `\` interchangeably.

CVSS v3.0 8.3 HIGH
CVSS v2.0 7.5 HIGH

8.3^/10

CVSS v3.0 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact LOW

Scope CHANGED

7.5^/10

CVSS v2.0 : HIGH

Vector : AV:N/AC:L/Au:N/C:P/I:P/A:P

Exploitability : 10.0 / Impact : 6.4

Access Vector NETWORK

Access Complexity LOW

Authentication NONE

Confidentiality Impact PARTIAL

Integrity Impact PARTIAL

Availability Impact PARTIAL

References

Link	Resource
https://github.com/envoyproxy/envoy/security/advisories/GHSA-4987-27fx-x6cf	Mitigation Third Party Advisory

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Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:envoyproxy:envoy::::::::
	cpe:2.3:a:envoyproxy:envoy::::::::
	cpe:2.3:a:envoyproxy:envoy::::::::
	cpe:2.3:a:envoyproxy:envoy::::::::

Information

Published : 2021-05-28 14:15

Updated : 2021-12-10 10:10

NVD link : CVE-2021-29492

Mitre link : CVE-2021-29492

JSON object : View

CWE

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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Products Affected

envoyproxy

envoy

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