Review reviewHigh

CVE-2026-47221

envoyproxy envoy

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.18.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, the router filter contains a null pointer dereference vulnerability when handling HTTP 303 (See Other) internal redirects for body-less non-GET/HEAD requests. When a POST, PUT, DELETE, or PATCH request without a body is sent to a route configured with internal redirect policy that includes 303 in redirect_response_codes, and the upstream responds with HTTP 303, the redirect handling code attempts to drain a request body buffer that was never allocated...

CVSS: 7.5
EPSS: 0.33%
CISA KEV: Not listed
Published: 2026.06.27

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.33%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: envoyproxy envoy
Affected versions: >= 1.38.0, < 1.38.3, >= 1.37.0, < 1.37.5, >= 1.36.0, < 1.36.9, >= 1.18.0, < 1.35.13, >= 1.18.0 < 1.35.13, >= 1.36.0 < 1.36.9, >= 1.37.0 < 1.37.5, >= 1.38.0 < 1.38.3
Fixed versions: 1.35.13, 1.36.9, 1.37.5, 1.38.3

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that envoyproxy envoy and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-476