A use-after-free (UAF) vulnerability in Envoy's DNS cache causes abnormal process termination. Envoy may reallocate memory when processing a pending DNS resolution, causing list iterator to reference freed memory.
The vulnerability exists in Envoy's Dynamic Forward Proxy implementation starting from version v1.34.0. The issue occurs when a completion callback for a DNS resolution triggers new DNS resolutions or removes existing pending resolutions. This condition may occur in the following configuration:
envoy.reloadable_features.dfp_cluster_resolves_hosts runtime flag is enabled.Denial of service due to abnormal process termination.
Request to Envoy configured as indicated above.
Users should upgrade to v1.35.1 or v1.34.5.
Set the envoy.reloadable_features.dfp_cluster_resolves_hosts runtime flag to false.
Abnormal process termination with the Envoy::Event::DispatcherImpl::runPostCallbacks() frame in the call stack.
Rohit Agrawal (agrawroh) (rohit.agrawal@databricks.com)
{
"cwe_ids": [
"CWE-416"
],
"github_reviewed": true,
"github_reviewed_at": "2025-09-15T16:46:37Z",
"nvd_published_at": "2025-09-03T00:15:30Z",
"severity": "HIGH"
}