What’s Vulnerable › Vulnerabilities

CVE-2021-43824: Null pointer dereference in envoy

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-02-22 · updated 2026-06-17
• Weakness: CWE-476

Description

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.

Affected products

• envoyproxy envoy: before 1.18.6; from 1.19.0 before 1.19.3; from 1.20.0 before 1.20.2; from 1.21.0 before 1.21.1 — fixed in 1.18.6, 1.19.3, 1.20.2, 1.21.1

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.18.6, 1.19.3, 1.20.2, 1.21.1. Check the vendor advisory for mitigations.

References

• https://github.com/envoyproxy/envoy/commit/9371333230b1a6e1be2eccf4868771e11af6253a
• https://github.com/envoyproxy/envoy/security/advisories/GHSA-vj5m-rch8-5r2p
• https://github.com/envoyproxy/envoy/commit/9371333230b1a6e1be2eccf4868771e11af6253a
• https://github.com/envoyproxy/envoy/security/advisories/GHSA-vj5m-rch8-5r2p

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