How severe is CVE-2026-73553?

CVE-2026-73553 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2026-73553 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-73553?

CVE-2026-73553 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-73553?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-73553 published?

CVE-2026-73553 was published on 2026-09-21 and last updated on 2026-10-05.

CVE-2026-73553

CVE-2026-73553 is a high-severity vulnerability in Envoyproxy Envoy with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-436.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-436
Affected product: Envoyproxy Envoy
Published: 2026-09-21
Last modified: 2026-10-05

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.

Frequently asked questions

What is CVE-2026-73553?: 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.
How severe is CVE-2026-73553?: CVE-2026-73553 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2026-73553 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-73553?: CVE-2026-73553 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-73553?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-73553 published?: CVE-2026-73553 was published on 2026-09-21 and last updated on 2026-10-05.

References

Affected products (1)

cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*

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