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HIGH severity

CVE-2025-54588 — envoy

HIGH

CVE-2025-54588 is a high-severity (CVSS 7.5) Use After Free vulnerability in github.com/envoyproxy/envoy. A fix is available for github.com/envoyproxy/envoy — see the affected versions and patch details below.

Envoy: Race condition in Dynamic Forward Proxy leads to use-after-free and segmentation faults

Also known asBIT-envoy-2025-54588GHSA-g9vw-6pvx-7gmw
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-54588.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk+0.02%
Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk
0.00%0.33%0.66%1.00%0.0%0.5%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected
🐹github.com/envoyproxy/envoy🐹github.com/envoyproxy/envoy

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

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) ([email protected])

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/envoyproxy/envoy≥ 1.35.0&&< 1.35.11.35.1go get github.com/envoyproxy/envoy@v1.35.1
🐹Gogithub.com/envoyproxy/envoy≥ 1.34.0&&< 1.34.51.34.5go get github.com/envoyproxy/envoy@v1.34.5

Affected Products

1 product · 2 configurations
Application
envoyenvoyproxy
≥ 1.34.0 && < 1.34.5
1 version
1.35.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/envoyproxy/envoy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/envoyproxy/envoy to 1.35.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-54588 is resolved across your whole dependency graph.

  3. Workarounds

    Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant
Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Source: Red Hat security advisory for CVE-2025-54588 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat OpenShift Service Mesh 3.0openshift-service-mesh/istio-proxyv2-rhel9:1.24.6-1757566151RHSA-2025:16040
Red Hat OpenShift Service Mesh 3.1openshift-service-mesh/istio-proxyv2-rhel9:1.26.4-1757524855RHSA-2025:16044

Frequently Asked Questions

### 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_
O3 Security · Impact-Aware SCA

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CVE-2025-54588: envoy DoS — Fixed in 1.35.1