CVE-2026-48706 Envoy Heap Buffer Overflow in TcpStatsdSink
Attacker can cause heap buffer overflow and potential RCE in Envoy by sending long request paths when grpc_stats filter is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-48706?
CVE-2026-48706 is a medium-severity memory corruption vulnerability in Envoyproxy Envoy, published on 26 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-120
Which versions are affected by CVE-2026-48706?
1 open source package ship an affected version, including envoy. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
envoy Bitnami | From 1.34.0 | 1.35.13, 1.36.9, 1.37.5, 1.38.3 |
Products include Envoyproxy Envoy.
How do I fix CVE-2026-48706?
Upgrade envoy to a fixed version for your release line: 1.35.13, 1.36.9, 1.37.5 or 1.38.3.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-48706 being exploited?
There is no known exploitation of CVE-2026-48706 in the wild and no public exploit code.
Other vulnerabilities in Envoyproxy Envoy
Sources
Also known as BIT-envoy-2026-48706, GHSA-7q3f-gwg7-j8g4.