Directory Traversal Affecting envoyproxy/envoy package, versions [,1.15.5)[1.16.0,1.16.4)[1.17.0,1.17.3)[1.18.0,1.18.3)


Severity

Recommended
0.0
high
0
10

CVSS assessment made by Snyk's Security Team. Learn more

Threat Intelligence

EPSS
0.27% (68th percentile)

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  • Snyk IDSNYK-UNMANAGED-ENVOYPROXYENVOY-2365509
  • published26 Jan 2022
  • disclosed28 May 2021
  • creditUnknown

Introduced: 28 May 2021

CVE-2021-29492  (opens in a new tab)
CWE-22  (opens in a new tab)

How to fix?

Upgrade envoyproxy/envoy to version 1.15.5, 1.16.4, 1.17.3, 1.18.3 or higher.

Overview

Affected versions of this package are vulnerable to Directory Traversal. 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.</h3>

References

CVSS Scores

version 3.1