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MEDIUM severity

Envoy Gateway: Wasm HTTP fetch decompresses gzip without output-size limitGHSA-cxpq-8v7q-cg56

MEDIUM

GHSA-cxpq-8v7q-cg56 is a medium-severity (CVSS 6.5) CWE-789 vulnerability in github.com/envoyproxy/gateway. A fix is available for github.com/envoyproxy/gateway — see the affected versions and patch details below.

Also known asBIT-envoy-gateway-2026-53716CVE-2026-53716GO-2026-6006
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • 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 GHSA-cxpq-8v7q-cg56.

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs53th percentile — riskier than 53% of all scored CVEsHighest risk
0.21%0.55%0.88%1.22%0.7%0.7%Oct 26Oct 26

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

How urgent is this, really

GHSA-cxpq-8v7q-cg56 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

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

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

Vulnerability report without repro case. Repro case may be added later after harness is complete.

Preconditions (4):

  • Tenant can create EnvoyExtensionPolicy (baseline)
  • Attacker hosts a gzip-bomb at a reachable URL
  • sha256 unset (optional field; check is post-decompression anyway)
  • No operator Wasm-URL allowlist (none exists in code)

Description

getFileFromGZ calls io.ReadAll on a raw gzip.Reader (httpfetcher.go:216) with no output bound, while the compressed input is capped at 256 MiB (httpfetcher.go:139). The bytes originate from a tenant-controlled EnvoyExtensionPolicy.spec.wasm[].code.http.url (envoyextensionpolicy.go:1077 → cache.go:248 → httpfetcher.go:147 → :233), so an untrusted tenant can point at a ~10 MiB gzip-of-zeros and force ~10 GiB allocation in the shared controller process. All candidate guards execute either before the body is buffered or after decompression. OOM-kills, restarts, re-reconciles same CR, crash-loops — persistent cross-tenant control-plane outage with PR:L/AC:L and scope change → HIGH despite availability-only.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/envoyproxy/gateway≥ 1.8.0-rc.0&&< 1.8.11.8.1go get github.com/envoyproxy/gateway@v1.8.1
🐹Gogithub.com/envoyproxy/gatewayall versions1.7.4go get github.com/envoyproxy/gateway@v1.7.4

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/gateway, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/envoyproxy/gateway to 1.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cxpq-8v7q-cg56 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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 HatModerate

RH Connectivity Link includes an affected Envoy Gateway version. Exploitation requires a tenant able to create an EnvoyExtensionPolicy referencing a reachable compressed Wasm payload, potentially causing controller OOM termination and cross-tenant control-plane disruption.

Workaround published by Red Hat
Restrict creation of EnvoyExtensionPolicy resources and constrain operator access to approved Wasm URLs until an updated Envoy Gateway version is available.
Source: Red Hat security advisory for GHSA-cxpq-8v7q-cg56 (CC BY 4.0)

Frequently Asked Questions

Vulnerability report without repro case. Repro case may be added later after harness is complete. **Preconditions (4):** - Tenant can create EnvoyExtensionPolicy (baseline) - Attacker hosts a gzip-bomb at a reachable URL - sha256 unset (optional field; check is post-decompression anyway) - No operator Wasm-URL allowlist (none exists in code) **Description** getFileFromGZ calls io.ReadAll on a raw gzip.Reader (httpfetcher.go:216) with no output bound, while the compressed input is capped at 256 MiB (httpfetcher.go:139). The bytes originate from a tenant-controlled EnvoyExtensionPolicy.spec.w
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Envoy Gateway: Wasm HTTP fetch decompresses gzip…