Asymmetric Resource Consumption (Amplification) Affecting envoyproxy/envoy package, versions [,1.35.11)[1.36.0,1.36.7)[1.37.0,1.37.3)[1.38.0,1.38.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-ENVOYPROXYENVOY-17339200
- published15 Jun 2026
- disclosed4 Jun 2026
- creditRyoga Yamashita
Introduced: 4 Jun 2026
CVE-2026-47774 (opens in a new tab)How to fix?
Upgrade envoyproxy/envoy to version 1.35.11, 1.36.7, 1.37.3, 1.38.1 or higher.
Overview
Affected versions of this package are vulnerable to Asymmetric Resource Consumption (Amplification) via the cookie header size bypass and HPACK amplification. An attacker can cause resource exhaustion and disrupt service availability by sending specially crafted HPACK-compressed headers or initiating Slowloris-style attacks that overwhelm the server with concurrent streams and large header lists.
Workaround
This vulnerability can be mitigated by disabling HTTP/2 support where not required, deploying behind a CDN or reverse proxy that can absorb or rate-limit such attacks, or limiting the maximum number of concurrent streams and header list size via configuration.