CVE-2026-31838
Authorization Bypass via Envoy RBAC Header Matching in Istio
Publication date: 2026-03-10
Last updated on: 2026-04-07
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| istio | istio | to 1.27.8 (exc) |
| istio | istio | From 1.28.0 (inc) to 1.28.5 (exc) |
| istio | istio | From 1.29.0 (inc) to 1.29.1 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-863 | The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in Istio's Envoy RBAC header matching before versions 1.29.1, 1.28.5, and 1.27.8. It allows an attacker to bypass authorization policies that rely on HTTP headers containing multiple values. By crafting requests with multiple header values, the attacker can cause Envoy to evaluate the header differently than intended, potentially bypassing authorization checks.
How can this vulnerability impact me? :
The vulnerability can allow unauthorized requests to reach protected services when authorization policies depend on header-based matching conditions. This means attackers could gain access to services or data that should be restricted, potentially leading to unauthorized actions or data exposure.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade Istio to one of the fixed versions: 1.29.1, 1.28.5, or 1.27.8.