CVE-2025-62409: 
Envoy vulnerability analysis and mitigation

CVE-2025-62409 affects Envoy, a cloud-native, open source edge and service proxy. The vulnerability was discovered and disclosed on October 15, 2025. The affected versions are <= 1.36.0, and the issue has been patched in versions 1.36.1, 1.35.5, 1.34.9, and 1.33.11 (GitHub Advisory).

The vulnerability occurs when large requests and responses trigger TCP connection pool crashes due to flow control management in Envoy. Specifically, the issue manifests when a connection is closing but upstream data is still incoming, resulting in a buffer watermark callback nullptr reference. The vulnerability impacts TCP proxy and HTTP 1 & 2 mixed use cases based on ALPN. The vulnerability has been assigned a CVSS v4.0 score of 6.6 (Medium) with vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U (NVD).

The vulnerability can lead to Denial of Service (DoS) and system crashes. This is particularly concerning for systems using Envoy as their edge or service proxy, as it could potentially disrupt service availability when exploited (GitHub Advisory).

The recommended mitigation is to upgrade to the patched versions: 1.36.1, 1.35.5, 1.34.9, or 1.33.11. These versions contain fixes for the vulnerability (GitHub Advisory).