Description
Envoy is a cloud-native, open source edge and service proxy. Prior to 1.36.1, 1.35.5, 1.34.9, and 1.33.10, large requests and responses can potentially trigger TCP connection pool crashes due to flow control management in Envoy. It will happen when the connection is closing but upstream data is still coming, resulting in a buffer watermark callback nullptr reference. The vulnerability impacts TCP proxy and HTTP 1 & 2 mixed use cases based on ALPN. This vulnerability is fixed in 1.36.1, 1.35.5, 1.34.9, and 1.33.10.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| envoyproxy | envoy | >= 1.36.0, < 1.36.1, >= 1.35.0, < 1.35.5, >= 1.34.0, < 1.34.9, < 1.33.10 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | istioctl | 1.27.3-1.1 | openSUSE-SU-2025:15655-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | ecs-service-connect-agent | v1.34.4.2-1.amzn2023 | ALAS2023-2025-1357 |
Advisories 3
- openSUSE-SU-2025:15655-1 istioctl-1.27.3-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- ALAS2023-2025-1357 Important: ecs-service-connect-agent security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jan 7, 2026
- WID-SEC-2025-2433 Google Cloud Platform (Envoy Proxy):: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Jan 5, 2026