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, a vulnerability exists in Envoy's TCP StatsD sink (TcpStatsdSink), where the thread-local flusher buffer can be overflowed by exceptionally long statistic names (e.g., >16KiB). During formatting, TcpStatsdSink reserves a single contiguous memory slice of 16KiB (FLUSH_SLICE_SIZE_BYTES). If formatting a single metric exceeds the remaining capacity, the flusher initiates a buffer rotation but incorrectly continues to allocate another fixed 16KiB slice. If an attacker can trigger a statistic name longer than 16KiB—for example, by sending an HTTP or gRPC request with an extremely long request path (:path) that is recorded by the grpc_stats filter configured with stats_for_all_methods: true—the flusher will attempt to copy the metric name using memcpy operations beyond the allocated heap buffer boundaries. This leads to a heap write overflow, which can cause immediate denial-of-service (process crash) or potential remote code execution (RCE). This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.

A flaw was found in Envoy, an open-source edge and service proxy. An attacker can exploit a heap write overflow vulnerability in Envoy's TCP StatsD sink by sending exceptionally long statistic names, such as those found in HTTP or gRPC request paths. This can lead to a denial-of-service, causing the process to crash, and potentially enable remote code execution.

A Moderate-severity heap write overflow in Envoy's TCP StatsD sink can cause a denial of service in Red Hat OpenShift Service Mesh. Exploitation requires an attacker to send exceptionally long statistic names, typically via HTTP or gRPC request paths, making the attack complex and limiting its immediate impact to service availability. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. OpenShift Service Mesh 2 Will not fix openshift-service-mesh/proxyv2-rhel9 OpenShift Service Mesh 3 Affected openshift-service-mesh/istio-proxyv2-rhel9 https://www.cve.org/CVERecord?id=CVE-2026-48706 https://nvd.nist.gov/vuln/detail/CVE-2026-48706 https://github.com/envoyproxy/envoy/security/advisories/GHSA-7q3f-gwg7-j8g4