CVE-2026-47774
Full vulnerability record from the local CVENow database.
Description
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a vulnerability in Envoy's HTTP/2 downstream request processing allows an unauthenticated remote client to trigger excessive memory consumption, potentially resulting in OOM termination of the Envoy process and denial of service. The issue arises from the combination of two behaviors. First, cookie header bytes are not fully accounted for during request header size validation in Envoy. Second, HPACK header block limits in oghttp2/quiche are enforced on encoded bytes without a corresponding limit on total decoded header size. Together, these behaviors allow a malicious client to cause large decoded header allocations while bypassing the intended request header size protections. Versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1 contain a fix. No complete workaround is known short of applying a fix. Possible temporary mitigations include disabling downstream HTTP/2 where operationally feasible; enforcing stricter request header and cookie limits before traffic reaches Envoy; and monitoring Envoy memory usage for abnormal growth under HTTP/2 traffic.
Severity
HIGH
CVSS score
7.5
(v3.1)
Vulnerability status
Analyzed
Source identifier
Published
2026-06-17 18:18:02.643000
Last modified
2026-10-26 11:10:00.157000
View original CVE JSON
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"sourceIdentifier": "[email protected]",
"published": "2026-06-17T18:18:02.643",
"lastModified": "2026-10-26T11:10:00.157",
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"value": "Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a vulnerability in Envoy's HTTP/2 downstream request processing allows an unauthenticated remote client to trigger excessive memory consumption, potentially resulting in OOM termination of the Envoy process and denial of service. The issue arises from the combination of two behaviors. First, cookie header bytes are not fully accounted for during request header size validation in Envoy. Second, HPACK header block limits in oghttp2/quiche are enforced on encoded bytes without a corresponding limit on total decoded header size. Together, these behaviors allow a malicious client to cause large decoded header allocations while bypassing the intended request header size protections. Versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1 contain a fix. No complete workaround is known short of applying a fix. Possible temporary mitigations include disabling downstream HTTP/2 where operationally feasible; enforcing stricter request header and cookie limits before traffic reaches Envoy; and monitoring Envoy memory usage for abnormal growth under HTTP/2 traffic."
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"value": "Envoy es un proxy de borde y de servicio de código abierto diseñado para aplicaciones nativas de la nube. Antes de las versiones 1.35.11, 1.36.7, 1.37.3 y 1.38.1, una vulnerabilidad en el procesamiento de solicitudes HTTP/2 descendentes de Envoy permite a un cliente remoto no autenticado activar un consumo excesivo de memoria, lo que podría resultar en la terminación OOM del proceso de Envoy y denegación de servicio. El problema surge de la combinación de dos comportamientos. Primero, los bytes del encabezado de la cookie no se contabilizan completamente durante la validación del tamaño del encabezado de la solicitud en Envoy. Segundo, los límites del bloque de encabezado HPACK en oghttp2/quiche se aplican a los bytes codificados sin un límite correspondiente en el tamaño total del encabezado decodificado. Juntos, estos comportamientos permiten a un cliente malicioso causar grandes asignaciones de encabezados decodificados mientras elude las protecciones de tamaño de encabezado de solicitud previstas. Las versiones 1.35.11, 1.36.7, 1.37.3 y 1.38.1 contienen una corrección. No se conoce ninguna solución alternativa completa que no sea aplicar una corrección. Las posibles mitigaciones temporales incluyen deshabilitar HTTP/2 descendente donde sea operacionalmente factible; aplicar límites más estrictos para los encabezados de solicitud y las cookies antes de que el tráfico llegue a Envoy; y monitorear el uso de memoria de Envoy para detectar un crecimiento anormal bajo tráfico HTTP/2."
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