What’s Vulnerable › Vulnerabilities

CVE-2026-47220: Envoy: Segmentation fault when using %REQUESTED_SERVER_NAME% in log format

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-06-26 · updated 2026-10-25
• Weakness: CWE-476

Description

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.37.0 until 1.37.5 and 1.38.3, when the %REQUESTED_SERVER_NAME(X:Y)% is used in log format and host related options is specified, like HOST_FIRST, SNI_FIRST, it's possible to crash Envoy when the specified host header is missing in the request headers. This vulnerability is fixed in 1.37.5 and 1.38.3.

Affected products

• envoyproxy envoy: from 1.37.0 before 1.37.5; from 1.38.0 before 1.38.3 — fixed in 1.37.5, 1.38.3

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.37.5, 1.38.3. Check the vendor advisory for mitigations.

References

• https://github.com/envoyproxy/envoy/security/advisories/GHSA-j9wh-4qfm-wf2v
• https://access.redhat.com/security/cve/CVE-2026-47220
• https://bugzilla.redhat.com/show_bug.cgi?id=2493652
• https://github.com/envoyproxy/envoy/security/advisories/GHSA-j9wh-4qfm-wf2v
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47220.json

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