Vulnerability Database

296,733

Total vulnerabilities in the database

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.

  • Published: May 28, 2021
  • Updated: Apr 14, 2023
  • CVE: CVE-2021-29492
  • Severity: High
  • Exploit:

CVSS v3:

  • Severity: High
  • Score: 8.3
  • AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L

CVSS v2:

  • Severity: High
  • Score: 7.5
  • AV:N/AC:L/Au:N/C:P/I:P/A:P

CWEs:

OWASP TOP 10:

Software From Fixed in
envoyproxy / envoy 1.18.0 1.18.3
envoyproxy / envoy 1.16.0 1.16.4
envoyproxy / envoy - 1.15.5
envoyproxy / envoy 1.17.0 1.17.3