VYPR
Medium severity5.8NVD Advisory· Published Aug 24, 2021· Updated Jun 17, 2026

CVE-2021-32778

CVE-2021-32778

Description

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.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected products

5
  • Envoyproxy/Envoy3 versions
    cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*+ 2 more
    • cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*range: >=1.16.0,<1.16.5
    • cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*
    • (no CPE)range: >= 1.19.0, < 1.19.1
  • Envoy/envoyllm-fuzzy
    Range: <1.19.1, <1.18.4, <1.17.4, <1.16.5
  • osv-coords
    Range: >= 1.16.0, < 1.16.5

Patches

Vulnerability mechanics

References

2

News mentions

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