Envoy is a cloud-native high-performance proxy. Versions of envoy prior to 1.22.1 are subject to a segmentation fault in the GrpcHealthCheckerImpl. Envoy can perform various types of upstream health checking. One of them uses gRPC. Envoy also has a feature which can “hold” (prevent removal) upstream hosts obtained via service discovery until configured active health checking fails. If an attacker controls an upstream host and also controls service discovery of that host (via DNS, the EDS API, etc.), an attacker can crash Envoy by forcing removal of the host from service discovery, and then failing the gRPC health check request. This will crash Envoy via a null pointer dereference. Users are advised to upgrade to resolve this vulnerability. Users unable to upgrade may disable gRPC health checking and/or replace it with a different health checking type as a mitigation.

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions Envoy does not restrict the set of certificates it accepts from the peer, either as a TLS client or a TLS server, to only those certificates that contain the necessary extendedKeyUsage (id-kp-serverAuth and id-kp-clientAuth, respectively). This means that a peer may present an e-mail certificate (e.g. id-kp-emailProtection), either as a leaf certificate or as a CA in the chain, and it will be accepted for TLS. This is particularly bad when combined with the issue described in pull request #630, in that it allows a Web PKI CA that is intended only for use with S/MIME, and thus exempted from audit or supervision, to issue TLS certificates that will be accepted by Envoy. As a result Envoy will trust upstream certificates that should not be trusted. There are no known workarounds to this issue. Users are advised to upgrade.

Envoy is an open source edge and service proxy, designed for cloud-native applications. The default_validator.cc implementation used to implement the default certificate validation routines has a "type confusion" bug when processing subjectAltNames. This processing allows, for example, an rfc822Name or uniformResourceIndicator to be authenticated as a domain name. This confusion allows for the bypassing of nameConstraints, as processed by the underlying OpenSSL/BoringSSL implementation, exposing the possibility of impersonation of arbitrary servers. As a result Envoy will trust upstream certificates that should not be trusted.

Envoy is an open source edge and service proxy, designed for cloud-native applications. The envoy common router will segfault if an internal redirect selects a route configured with direct response or redirect actions. This will result in a denial of service. As a workaround turn off internal redirects if direct response entries are configured on the same listener.

Envoy is an open source edge and service proxy, designed for cloud-native applications. Envoy's tls allows re-use when some cert validation settings have changed from their default configuration. The only workaround for this issue is to ensure that default tls settings are used. Users are advised to upgrade.

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions of Envoy a crash occurs when configured for :ref:`upstream tunneling <envoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config>` and the downstream connection disconnects while the the upstream connection or http/2 stream is still being established. There are no workarounds for this issue. Users are advised to upgrade.

Envoy is an open source edge and service proxy, designed for cloud-native applications. Sending a locally generated response must stop further processing of request or response data. Envoy tracks the amount of buffered request and response data and aborts the request if the amount of buffered data is over the limit by sending 413 or 500 responses. However when the buffer overflows while response is processed by the filter chain the operation may not be aborted correctly and result in accessing a freed memory block. If this happens Envoy will crash resulting in a denial of service.

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions a crafted request crashes Envoy when a CONNECT request is sent to JWT filter configured with regex match. This provides a denial of service attack vector. The only workaround is to not use regex in the JWT filter. Users are advised to upgrade.

Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, contains two authorization related vulnerabilities CVE-2021-32777 and CVE-2021-32779. This may lead to incorrect routing or authorization policy decisions. With specially crafted requests, incorrect authorization or routing decisions may be made by Pomerium. Pomerium v0.14.8 and v0.15.1 contain an upgraded envoy binary with these vulnerabilities patched. This issue can only be triggered when using path prefix based policy. Removing any such policies should provide mitigation.

Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, incorrectly handles resetting of HTTP/2 streams with excessive complexity. This can lead to high CPU utilization when a large number of streams are reset. This can result in a DoS condition. Pomerium versions 0.14.8 and 0.15.1 contain an upgraded envoy binary with this vulnerability patched.

Pomerium is an open source identity-aware access proxy. Envoy, which Pomerium is based on, can abnormally terminate if an H/2 GOAWAY and SETTINGS frame are received in the same IO event. This can lead to a DoS in the presence of untrusted *upstream* servers. 0.15.1 contains an upgraded envoy binary with this vulnerability patched. If only trusted upstreams are configured, there is not substantial risk of this condition being triggered.

Envoy is a cloud-native edge/middle/service proxy. Envoy does not decode escaped slash sequences `%2F` and `%5C` in HTTP URL paths in versions 1.18.2 and before. A remote attacker may craft a path with escaped slashes, e.g. `/something%2F..%2Fadmin`, to bypass access control, e.g. a block on `/admin`. A backend server could then decode slash sequences and normalize path and provide an attacker access beyond the scope provided for by the access control policy. ### Impact Escalation of Privileges when using RBAC or JWT filters with enforcement based on URL path. Users with back end servers that interpret `%2F` and `/` and `%5C` and `\` interchangeably are impacted. ### Attack Vector URL paths containing escaped slash characters delivered by untrusted client. Patches in versions 1.18.3, 1.17.3, 1.16.4, 1.15.5 contain new path normalization option to decode escaped slash characters. As a workaround, if back end servers treat `%2F` and `/` and `%5C` and `\` interchangeably and a URL path based access control is configured, one may reconfigure the back end server to not treat `%2F` and `/` and `%5C` and `\` interchangeably.

Envoy before 1.16.1 mishandles dropped and truncated datagrams, as demonstrated by a segmentation fault for a UDP packet size larger than 1500.

Envoy before 1.16.1 logs an incorrect downstream address because it considers only the directly connected peer, not the information in the proxy protocol header. This affects situations with tcp-proxy as the network filter (not HTTP filters).