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GHSA-g9vw-6pvx-7gmw

HighCVSS 7.5 / 10
Published Sep 15, 2025·Last modified Sep 15, 2025
Affected Components(0)

No affected components available

Description

Summary

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.

Details

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:

  1. Dynamic Forwarding Filter is enabled.
  2. envoy.reloadable_features.dfp_cluster_resolves_hosts runtime flag is enabled.
  3. The Host header is modified between the Dynamic Forwarding Filter and Router filters.

Impact

Denial of service due to abnormal process termination.

Attack vector(s)

Request to Envoy configured as indicated above.

Patches

Users should upgrade to v1.35.1 or v1.34.5.

Workaround

Set the envoy.reloadable_features.dfp_cluster_resolves_hosts runtime flag to false.

Detection

Abnormal process termination with the Envoy::Event::DispatcherImpl::runPostCallbacks() frame in the call stack.

Credits

Rohit Agrawal (agrawroh) (rohit.agrawal@databricks.com)

Risk Scores
Base Score
7.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
6.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.44%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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