CVE-2026-73551
MEDIUMDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Exploit Intelligence
Moderate risk: more likely to be exploited than 43% of all known CVEs.
References
Related Vulnerabilities
Other CWE-647 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-43939 | High | 8.6 | 92% | KEV | Fix |
| CVE-2025-64500 | High | 7.3 | 1.3% | - | Fix |
| CVE-2026-62685 | High | 8.1 | 0.6% | - | - |
| CVE-2026-5222 | Low | 6.5 | 0.5% | - | Fix |
| CVE-2026-80515 | High | 8.9 | 0.5% | - | - |
| CVE-2026-59731 | High | 8.2 | 0.5% | - | - |
Common questions
How do I fix CVE-2026-73551?
No published fix for CVE-2026-73551 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-73551 being actively exploited?
Not that we know of. CVE-2026-73551 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.53% is the estimated probability that it will be exploited in the next 30 days. That is higher than 43% of all scored CVEs.
How severe is CVE-2026-73551?
CVE-2026-73551 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-28.