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TI-2021-19630 Aliases CVE-2021-43824

Null pointer dereference in envoy

Priority MEDIUM 41CWE-476Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-476.

Summary

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions a crafted request crashes Envoy when a CONNECT request is sent to JWT filter configured with regex match. This provides a denial of service attack vector. The only workaround is to not use regex in the JWT filter. Users are advised to upgrade.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01062 64th percentileScored 2026-11-07
Fix Fixed envoy (envoyproxy): 1.20.2, 1.19.3, 1.18.6 +1Red Hat: 2 advisories

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
envoyproxyenvoy1.20.0 to before 1.20.2; 1.19.0 to before 1.19.3; before 1.18.6; 1.21.0 to before 1.21.11.20.2, 1.19.3, 1.18.6, 1.21.1Patch availableCNA
  • envoy Vendorenvoyproxy Affected 1.20.0 to before 1.20.2; 1.19.0 to before 1.19.3; before 1.18.6; 1.21.0 to before 1.21.1 Fixed in 1.20.2, 1.19.3, 1.18.6, 1.21.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*before 1.18.6; 1.19.0 to before 1.19.3; 1.20.0 to before 1.20.2; 1.21.0 to before 1.21.1Vulnerableenvoyproxy
  • cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* Versions before 1.18.6; 1.19.0 to before 1.19.3; 1.20.0 to before 1.20.2; 1.21.0 to before 1.21.1 Vulnerable ·envoyproxy

Remediation

  • Fix · CNA envoy (envoyproxy) Fixed in 1.20.2, 1.19.3, 1.18.6, 1.21.1

Red Hat 2 advisories

  • RHSA-2022:1275 Released 2022-04-07 · Red Hat rating Important
    Red Hat OpenShift Service Mesh 2.1.2 security update
    • OpenShift Service Mesh 2.1 servicemesh-2.1.2-4.el8, servicemesh-cni-2.1.2-4.el8, servicemesh-pilot-agent-2.1.2-4.el8 +3
  • RHSA-2022:1276 Released 2022-04-07 · Red Hat rating Important
    Red Hat OpenShift Service Mesh 2.0.9 security update
    • OpenShift Service Mesh 2.0 kiali-v1.24.7.redhat1-1.el8, servicemesh-2.0.9-3.el8, servicemesh-istioctl-2.0.9-3.el8 +6

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
OpenShift Service Mesh 2.0Fixed RHSA-2022:1276
OpenShift Service Mesh 2.1Fixed RHSA-2022:1275
Not affected: 2 products
  • OpenShift Service Mesh 2.0
  • OpenShift Service Mesh 2.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-43824

References

Patch 1

Advisory 1

  • 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