UpHeron
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Servers and applications

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…

Severity
High 8.3
Published
28 May 2021
Last changed
17 Jun 2026
Added to UpHeron
1 Nov 2026
Fixed in
1.15.5, 1.16.4, 1.17.3, 1.18.3
Sources
NVD

Affected software

SoftwareAffected versions
EnvoyServers and applications · cpe:a:envoyproxy:envoy
  • Every version before 1.15.5
  • From 1.16.0 before 1.16.4
  • From 1.17.0 before 1.17.3
  • From 1.18.0 before 1.18.3

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2021-29492
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2021-29492