CVE-2026-73551 Envoy: Path normalization does not handle dot and dotdot segments with parameters
Attackers can bypass path-based security policies in Envoy by using dot segments with parameters, requiring path normalization to be enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-73551?
CVE-2026-73551 is a medium-severity path traversal vulnerability in Envoyproxy Envoy, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-647
Which versions are affected by CVE-2026-73551?
1 open source package ship an affected version, including envoy. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
envoy Bitnami | All versions | 1.36.10, 1.37.6, 1.38.4, 1.39.1 |
Products include Envoyproxy Envoy.
How do I fix CVE-2026-73551?
Upgrade envoy to a fixed version for your release line: 1.36.10, 1.37.6, 1.38.4 or 1.39.1.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-73551 being exploited?
There is no known exploitation of CVE-2026-73551 in the wild and no public exploit code.
Other vulnerabilities in Envoyproxy Envoy
Sources
Also known as BIT-envoy-2026-73551, GHSA-2w8w-rfw7-8gg4, MINI-4jhq-xfpx-qqg4, MINI-6c7c-mq7m-8h73, MINI-6p7g-m37x-mvg8, MINI-c39h-p5qg-j46j.