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6.9
Istio: Unauthorized access to services through crafted HTTP requests
CVE-2026-31838
Summary
An attacker can bypass security checks and access protected services by crafting specific HTTP requests. This affects Istio versions prior to 1.29.1, 1.28.5, and 1.27.8. To fix this, upgrade to the latest version of Istio.
Original title
Istio is an open platform to connect, manage, and secure microservices. Prior to 1.29.1, 1.28.5, and 1.27.8, a vulnerability in Envoy RBAC header matching could allow authorization policy bypass wh...
Original description
Istio is an open platform to connect, manage, and secure microservices. Prior to 1.29.1, 1.28.5, and 1.27.8, a vulnerability in Envoy RBAC header matching could allow authorization policy bypass when policies rely on HTTP headers that may contain multiple values. An attacker could craft requests with multiple header values in a way that causes Envoy to evaluate the header differently than intended, potentially bypassing authorization checks. This may allow unauthorized requests to reach protected services when policies depend on such header-based matching conditions. This vulnerability is fixed in 1.29.1, 1.28.5, and 1.27.8.
nvd CVSS4.0
6.9
Vulnerability type
CWE-863
Incorrect Authorization
Published: 10 Mar 2026 · Updated: 14 Mar 2026 · First seen: 10 Mar 2026