Envoyproxy: >> Envoy >> 1.37.1 Security Vulnerabilities
Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.23.0 until 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a vulnerability has been identified in Envoy's zstd decompressor implementation (ZstdDecompressorImpl). When zstd decompression is enabled, processing a specially crafted, highly compressed zstd payload can lead to massive memory allocation. An attacker can exploit this to cause severe memory exhaustion, potentially resulting in an Out-Of-Memory (OOM) kill and Denial of Service (DoS) for the Envoy proxy. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
CVSS Score
7.5
EPSS Score
0.005
Published
2026-06-26
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, in cases where UDP DNS filter is configured with local resolution containing a name with the length of 255 octets or remote resolution for a name of 255 octets long can complete successfully, a query with such name will result in abnormal process termination. The abnormal process termination is triggered by an invalid runtime precondition that the query name is strictly less than 255 octets, contradicting DNS specification rfc1035#section-2.3.4 that the name can be 255 or less octets. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
CVSS Score
5.9
EPSS Score
0.004
Published
2026-06-26
Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.26.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, the envoy.filters.http.grpc_stats filter crashes (null pointer dereference / segfault) when a Connect protocol request (Content-Type: application/connect+proto or application/connect+json) hits a direct_response route. A single unauthenticated HTTP request crashes the Envoy process. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.
CVSS Score
6.5
EPSS Score
0.004
Published
2026-06-26
Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.34.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, Envoy crashes if an ext_proc server sends a single gRPC message containing multiple, specially crafted ProcessingResponse messages. This can occur when the first response in the batch causes the gRPC stream object to be destroyed, leading to a use-after-free error when Envoy attempts to process subsequent responses in the same gRPC message. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.
CVSS Score
6.5
EPSS Score
0.004
Published
2026-06-26
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.
CVSS Score
7.5
EPSS Score
0.008
Published
2026-06-17
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