CVE-2026-73551

5.3 MEDIUMpublic exploit available

Published 2026-09-21 · Updated 2026-09-21

AI risk analysis

Summary: The flaw allows path confusion by not properly normalizing URL segments with semicolons, potentially bypassing security policies.
Exploitability: Exploitation requires specific URL formatting and a misalignment in how upstream and Envoy interpret paths; moderately difficult.
Blast radius: If exploited, could lead to unauthorized access or policy bypass affecting cloud-native applications using Envoy as a proxy.
Prioritized remediation: Update to Envoy versions 1.36.10, 1.37.6, 1.38.4, or 1.39.1 to mitigate the vulnerability.

path-confusionsecurity-policy-bypasscloud-nativeproxy

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's URL normalization does not recognize dot and dotdot path segments when they carry semicolon parameters. A request such as /user/..;foo=bar/admin is therefore not canonicalized to /admin even when path normalization is enabled. If an upstream interprets the segment according to RFC 3986 while Envoy applies routing or RBAC to the uncollapsed path, a remote client can cause path confusion and bypass path-based security policy. The relevant scope boundary is that the security consequence depends on a downstream/upstream path interpretation mismatch or a path-based Envoy decision. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Weaknesses

CWE-647

Public exploit & PoC references

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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