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Excessive Iteration

CVE-2021-32778

Medium
5.8/10

Summary

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions envoy’s procedure for resetting a HTTP/2 stream has O(N^2) complexity, leading to high CPU utilization when a large number of streams are reset. Deployments are susceptible to Denial of Service when Envoy is configured with high limit on H/2 concurrent streams. An attacker wishing to exploit this vulnerability would require a client opening and closing a large number of H/2 streams. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to reduce time complexity of resetting HTTP/2 streams. As a workaround users may limit the number of simultaneous HTTP/2 dreams for upstream and downstream peers to a low number, i.e. 100.

  • LOW
  • NETWORK
  • NONE
  • CHANGED
  • NONE
  • NONE
  • NONE
  • LOW

CWE-834 - Excessive Iteration

The software performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.

References

Advisory Timeline

  • Published