CVE-2026-47220: Envoy: Segmentation fault when using %REQUESTED_SERVER_NAME% in log format
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 %REQUESTEDSERVERNAME(X:Y)% is used in log format and host related options is specified, like HOSTFIRST, SNIFIRST, 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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
envoyto a version that resolves this vulnerability.Fixed in 1.37.5 - Upgrade
Upgrade
envoyto a version that resolves this vulnerability.Fixed in 1.38.3
Event History
Frequently Asked Questions
What is the severity of CVE-2026-47220?
CVE-2026-47220 has a high severity rating of 7.5.
How do I fix CVE-2026-47220?
To mitigate CVE-2026-47220, update Envoy to versions 1.37.6, 1.38.4, or later.
What causes CVE-2026-47220?
CVE-2026-47220 is caused by a segmentation fault when using %REQUESTED_SERVER_NAME% in log formats with specific host related options.
What versions of Envoy are affected by CVE-2026-47220?
CVE-2026-47220 affects Envoy versions from 1.37.0 to 1.37.5 and 1.38.3.
Is CVE-2026-47220 a critical vulnerability?
While CVE-2026-47220 is serious, it specifically leads to a crash, thus making it a high but non-exploitative vulnerability.