CVE-2026-53716
MEDIUMCVE-2026-53716 is a medium-severity (CVSS 6.5) vulnerability in github.com/envoyproxy/gateway. O3 Security confirms whether CVE-2026-53716 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Envoy Gateway: Wasm HTTP fetch decompresses gzip without output-size limit
Real-World Exposure
github.com/envoyproxy/gateway🐹github.com/envoyproxy/gatewayReal-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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/envoyproxy/gateway | ≥ 1.8.0-rc.0&&< 1.8.1 | 1.8.1 |
| 🐹Go | github.com/envoyproxy/gateway | all versions | 1.7.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/envoyproxy/gateway. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 CVE-2026-53716 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-53716 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-53716. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-53716 in your dependencies?
O3 detects CVE-2026-53716 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.