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Envoy Gateway: Wasm HTTP fetch decompresses gzip without output-size limit

Moderate severity GitHub Reviewed Published Jun 5, 2026 in envoyproxy/gateway • Updated Jul 16, 2026

Package

gomod github.com/envoyproxy/gateway (Go)

Affected versions

>= 1.8.0-rc.0, < 1.8.1
< 1.7.4

Patched versions

1.8.1
1.7.4

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.

References

@zirain zirain published to envoyproxy/gateway Jun 5, 2026
Published to the GitHub Advisory Database Jul 16, 2026
Reviewed Jul 16, 2026
Last updated Jul 16, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(14th percentile)

Weaknesses

Memory Allocation with Excessive Size Value

The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. Learn more on MITRE.

CVE ID

CVE-2026-53716

GHSA ID

GHSA-cxpq-8v7q-cg56

Source code

Credits

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