Summary
Envoy Gateway: Wasm HTTP fetch decompresses gzip without output-size limit
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.
Impact
CVE-2026-53716 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.8.1, 1.7.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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github.com/envoyproxy/gateway to 1.8.1 or later; github.com/envoyproxy/gateway to 1.7.4 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-53716? CVE-2026-53716 is a medium-severity security vulnerability in github.com/envoyproxy/gateway (go), affecting versions >= 1.8.0-rc.0, < 1.8.1. It is fixed in 1.8.1, 1.7.4.
- How severe is CVE-2026-53716? CVE-2026-53716 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/envoyproxy/gateway are affected by CVE-2026-53716? github.com/envoyproxy/gateway (go) versions >= 1.8.0-rc.0, < 1.8.1 is affected.
- Is there a fix for CVE-2026-53716? Yes. CVE-2026-53716 is fixed in 1.8.1, 1.7.4. Upgrade to this version or later.
- Is CVE-2026-53716 exploitable, and should I be worried? Whether CVE-2026-53716 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-53716 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-53716?
- Upgrade
github.com/envoyproxy/gatewayto 1.8.1 or later - Upgrade
github.com/envoyproxy/gatewayto 1.7.4 or later
- Upgrade