Bug 2493676 (CVE-2026-48706)

Summary: CVE-2026-48706 envoy: Envoy Heap Buffer Overflow in TcpStatsdSink
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: kaycoth
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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.
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Description OSIDB Bzimport 2026-06-26 20:01:19 UTC 
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.