CVE-2026-73553

Q: How do I fix CVE-2026-73553?

Upgrade envoy to 1.39.1 or later.

Q: Is CVE-2026-73553 being actively exploited?

Not that we know of. CVE-2026-73553 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.51% is the estimated probability that it will be exploited in the next 30 days. That is higher than 43% of all scored CVEs.

Q: How severe is CVE-2026-73553?

CVE-2026-73553 has a CVSS v3 base score of 7.5, rated high. 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.

Q: What does CVE-2026-73553 affect?

Published advisories record a fix for envoy (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

HIGH

7.5

CVSS v3

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, When ignore_path_parameters_in_path_matching is enabled, Envoy's router strips the semicolon suffix before matching but the RBAC url_path matcher evaluates the raw path. A downstream request such as /admin;x can therefore miss a DENY rule for /admin while the router still selects the protected /admin backend. The inconsistent canonicalization allows an unauthenticated client to bypass path-based authorization. The relevant scope boundary is that the route option and a path-based RBAC rule must both be present, and the protected route must match after stripping. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

CWE-436

How to fix

Remediation Available

envoyNVD

Affected:>= 1.39.0, < 1.39.1Fixed in:1.39.1CVE-2026-73553derived from NVD

Affected:>= 1.38.0, < 1.38.4Fixed in:1.38.4CVE-2026-73553derived from NVD

Affected:< 1.36.10Fixed in:1.36.10CVE-2026-73553derived from NVD

Affected:>= 1.37.0, < 1.37.6Fixed in:1.37.6CVE-2026-73553derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.51%probability of exploitation in 30 days

43rdpercentile

Moderate risk: more likely to be exploited than 43% of all known CVEs.

References

Patch4

Exploit1

github.com

Release Notes4

Related Vulnerabilities

Other CWE-436 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-25292	Critical	9.8	65%	-	Fix
CVE-2022-37436	Medium	5.3	56%	-	Fix
CVE-2021-28474	High	8.8	51%	-	Fix
CVE-2025-25291	Critical	9.8	21%	-	Fix
CVE-2026-63030	Critical	9.8	11%	KEV	Fix
CVE-2019-17596	High	7.5	4.7%	-	Fix

Common questions

How do I fix CVE-2026-73553?

Upgrade envoy to 1.39.1 or later.

Is CVE-2026-73553 being actively exploited?

Not that we know of. CVE-2026-73553 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.51% 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-2026-73553?

CVE-2026-73553 has a CVSS v3 base score of 7.5, rated high. 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.

What does CVE-2026-73553 affect?

Published advisories record a fix for envoy (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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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 2026-10-05.