Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, a logic vulnerability in Envoys HTTP connection manager (FilterManager) that allows for Zombie Stream Filter Execution. This issue creates a Use-After-Free (UAF) or state-corruption window where filter callbacks are invoked on an HTTP stream that has already been logically reset and cleaned up. The vulnerability resides in source/common/http/filter_manager.cc within the FilterManager::decodeData method. The ActiveStream object remains valid in memory during the deferred deletion window. If a DATA frame arrives on this stream immediately after the reset (e.g., in the same packet processing cycle), the HTTP/2 codec invokes ActiveStream::decodeData, which cascades to FilterManager::decodeData. FilterManager::decodeData fails to check the saw_downstream_reset_ flag. It iterates over the decoder_filters_ list and invokes decodeData() on filters that have already received onDestroy(). This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.
Weakness
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Envoy | Envoyproxy | * | 1.34.13 (excluding) |
| Envoy | Envoyproxy | 1.35.0 (including) | 1.35.8 (excluding) |
| Envoy | Envoyproxy | 1.36.0 (including) | 1.36.5 (excluding) |
| Envoy | Envoyproxy | 1.37.0 (including) | 1.37.0 (including) |