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CVE-2026-31838 PUBLISHED CVSS 6.900000095367432 MEDIUM

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.

EPSS 0.04% · 11.7th percentile

Risk Scores

CVSS v4.0
6.900000095367432
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
EPSS Score
0.04%
11.7th percentile

Affected Products

VendorProductVersions
istioistio>= 1.29.0-alpha.0, < 1.29.1, >= 1.28.0-alpha.0, < 1.28.5, 0

Timeline

References

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