Read the docs
TI-2021-12447 Aliases CVE-2021-32780

Incorrect handling of H/2 GOAWAY followed by SETTINGS frames

Priority MEDIUM 40CWE-754Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions Envoy transitions a H/2 connection to the CLOSED state when it receives a GOAWAY frame without any streams outstanding. The connection state is transitioned to DRAINING when it receives a SETTING frame with the SETTINGS_MAX_CONCURRENT_STREAMS parameter set to 0. Receiving these two frames in the same I/O event results in abnormal termination of the Envoy process due to invalid state transition from CLOSED to DRAINING. A sequence of H/2 frames delivered by an untrusted upstream server will result in Denial of Service in the presence of untrusted **upstream** servers. Envoy versions 1.19.1, 1.18.4 contain fixes to stop processing of pending H/2 frames after connection transition to the CLOSED state.

Why it matters now

EPSS 0.0123 69th percentileScored 2026-11-07
Fix Fixed envoy (envoyproxy): 1.19.1, 1.18.4

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
envoyproxyenvoy1.19.0 to before 1.19.1; 1.18.0 to before 1.18.41.19.1, 1.18.4Patch availableCNA
  • envoy Vendorenvoyproxy Affected 1.19.0 to before 1.19.1; 1.18.0 to before 1.18.4 Fixed in 1.19.1, 1.18.4 Patch available CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*1.18.0 to before 1.18.4Vulnerableenvoyproxy
cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*1.19.0Vulnerableenvoyproxy
  • cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* Versions 1.18.0 to before 1.18.4 Vulnerable ·envoyproxy
  • cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:* Versions 1.19.0 Vulnerable ·envoyproxy

Remediation

  • Fix · CNA envoy (envoyproxy) Fixed in 1.19.1, 1.18.4

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Not affected: 2 products
  • OpenShift Service Mesh 1
  • OpenShift Service Mesh 2.0

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-32780

References

Advisory 2

  • TI-2026-79288 Out-of-bounds write in Google Brotli decoder KEVCVSS 4.0CRITICAL 9.2
  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
  • TI-2024-20001 HTTP/2: CPU exhaustion due to CONTINUATION frame flood CVSS 3.1HIGH 7.5
  • TI-2024-18524 HTTP/2: memory exhaustion due to CONTINUATION frame flood CVSS 3.1HIGH 7.5
  • TI-2023-12215 Envoy client may fake the header `x-envoy-original-path` CVSS 3.1CRITICAL 9.1
  • TI-2023-18002 Envoy vulnerable to OAuth2 credentials exploit with permanent validity CVSS 3.1CRITICAL 9.8
See all 126 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences