Id:
CVE-2021-29492
Comment
:
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.
CVSSv2 Score:
7.5
Access vector:
|
NETWORK
|
Access complexity:
|
LOW
|
Authentication:
|
NONE
|
Confidentiality impact:
|
PARTIAL
|
Integrity impact:
|
PARTIAL
|
Availability impact:
|
PARTIAL
|
CVSSv2 Vector:
AV:N/AC:L/Au:N/C:P/I:P/A:P
CVSSv3 Score:
8.3
Attack vector:
|
NETWORK
|
Attack complexity:
|
LOW
|
Privileges required:
|
NONE
|
User interaction:
|
NONE
|
Scope:
|
CHANGED
|
Confidentiality impact:
|
LOW
|
Integrity impact:
|
LOW
|
Availability impact:
|
LOW
|
CVSSv3 Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
References: