// For flags

CVE-2021-32780

Incorrect handling of H/2 GOAWAY followed by SETTINGS frames

Severity Score

7.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions Envoy transitions a H/2 connection to the CLOSED state when it receives a GOAWAY frame without any streams outstanding. The connection state is transitioned to DRAINING when it receives a SETTING frame with the SETTINGS_MAX_CONCURRENT_STREAMS parameter set to 0. Receiving these two frames in the same I/O event results in abnormal termination of the Envoy process due to invalid state transition from CLOSED to DRAINING. A sequence of H/2 frames delivered by an untrusted upstream server will result in Denial of Service in the presence of untrusted **upstream** servers. Envoy versions 1.19.1, 1.18.4 contain fixes to stop processing of pending H/2 frames after connection transition to the CLOSED state.

Envoy es un proxy L7 de código abierto y un bus de comunicación diseñado para grandes arquitecturas modernas orientadas a servicios. En las versiones afectadas, Envoy lleva a cabo una transición de una conexión H/2 al estado CLOSED cuando recibe una trama GOAWAY sin ningún flujo pendiente. El estado de la conexión pasa a DRAINING cuando recibe una trama SETTING con el parámetro SETTINGS_MAX_CONCURRENT_STREAMS ajustado a 0. Recibiendo estas dos tramas en el mismo evento de E/S resulta en una terminación anormal del proceso Envoy debido a una transición de estado no válida de CLOSED a DRAINING. Una secuencia de tramas H/2 entregada por un servidor upstream no confiable resultará en una Denegación de Servicio en presencia de servidores **upstream** no confiables. Envoy versiones 1.19.1 y 1.18.4, contienen correcciones para detener el procesamiento de las tramas H/2 pendientes después de la transición de la conexión al estado CLOSED.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-05-12 CVE Reserved
  • 2021-08-24 CVE Published
  • 2024-05-09 EPSS Updated
  • 2024-08-03 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-754: Improper Check for Unusual or Exceptional Conditions
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Envoyproxy
Search vendor "Envoyproxy"
 Envoy
Search vendor "Envoyproxy" for product "Envoy"
 >= 1.18.0 < 1.18.4
Search vendor "Envoyproxy" for product "Envoy" and version " >= 1.18.0 < 1.18.4"
-
Affected
Envoyproxy
Search vendor "Envoyproxy"
 Envoy
Search vendor "Envoyproxy" for product "Envoy"
 1.19.0
Search vendor "Envoyproxy" for product "Envoy" and version "1.19.0"
-
Affected