CVE-2026-47774
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.
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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.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 7.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 1.05%
- Percentil entre todas las CVEs puntuadas: 63
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access95 % - Impacto principal
T1499.004Application or System Exploitationimpact90 %
Vulnerabilidad en procesamiento remoto de solicitudes HTTP/2 sin autenticación (AV:N/PR:N/UI:N) que causa consumo excesivo de memoria y negación de servicio por agotamiento de recursos.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (2)
CWE
- CWE-405, CWE-770
- CWE-409
Referencias
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8
- http://www.openwall.com/lists/oss-security/2026/06/04/15
- https://access.redhat.com/errata/RHSA-2026:26210
- https://access.redhat.com/errata/RHSA-2026:26222
- https://access.redhat.com/errata/RHSA-2026:26231
- https://access.redhat.com/errata/RHSA-2026:26247
- https://access.redhat.com/errata/RHSA-2026:27114
- https://access.redhat.com/security/cve/CVE-2026-47774
- https://bugzilla.redhat.com/show_bug.cgi?id=2487465
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47774.json
JSON original (NVD)
Mostrar
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