CVE-2026-73551Network attack vector

Path-policy bypass via parameterized dot segments

Published Sep 21, 2026 · Updated Sep 21, 2026

URL path normalization in Envoy allows remote attackers to bypass path-based routing or RBAC via parameterized dot segments. The canonicalizer fails to treat segments beginning /.; and /..; as dot segments, leaving paths such as /user/..;foo=bar/admin uncollapsed. Exploitation requires normalize_path plus an upstream interpretation mismatch or a path-based Envoy decision, and can expose resources protected by routing or RBAC.

CVSS severity5.3
Medium
EPSS probability0.53%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

URL path normalization in Envoy allows remote attackers to bypass path-based routing or RBAC via parameterized dot segments. The canonicalizer fails to treat segments beginning /.; and /..; as dot segments, leaving paths such as /user/..;foo=bar/admin uncollapsed. Exploitation requires normalize_path plus an upstream interpretation mismatch or a path-based Envoy decision, and can expose resources protected by routing or RBAC.

The record

CVE
CVE-2026-73551
Published
Sep 21, 2026
Updated
Sep 21, 2026
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-647, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.36.10
  2. Affected versionversion=>= 1.37.0, < 1.37.6
  3. Affected versionversion=>= 1.38.0, < 1.38.4
  4. Affected versionversion=>= 1.39.0, < 1.39.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Envoy Proxy · Envoyversion=< 1.36.10; version=>= 1.37.0, < 1.37.6; version=>= 1.38.0, < 1.38.4; version=>= 1.39.0, < 1.39.1

Published CVSS scores

5.3GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-647Use of Non-Canonical URL Paths for Authorization Decisions
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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