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CVE-2026-73551

Envoy: Path normalization does not handle dot and dotdot segments with parameters

MEDIUM
5.3
CVSS Score
Published: September 21, 2026 at 08:17 PM UTC
Updated: October 5, 2026 at 02:06 PM UTC
1 product affected across 1 vendorEnvoy

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Envoy· Envoyproxy
95%
v < 1.36.10v < 1.37.6v < 1.38.4v < 1.39.11.37.0 ≤ v < 1.37.61.38.0 ≤ v < 1.38.41.39.0 ≤ v < 1.39.1
Affected range stops below 1.36.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.37.6, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.38.4, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.39.1, so it looks safe — our inference, not a vendor statement

References (9)

x_refsource_CONFIRMVendor Advisory
Source: cverecord
https://github.com/envoyproxy/envoy/security/advisories/GHSA-2w8w-rfw7-8gg4
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/28b6d60a6d96edeece121cac5be701eb46cc7f24
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/d40a68b0a30a003c4e0a9fd3af637f828b52c37b
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/e9d6c329f9a3ff19432bf39b60c601df7e3eda33
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/f74d1107c4f5c9679b66f7a03a6c5b75ddde1989
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/envoyproxy/envoy/releases/tag/v1.36.10
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/envoyproxy/envoy/releases/tag/v1.37.6
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/envoyproxy/envoy/releases/tag/v1.38.4

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-647

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