CVE-2021-39155— Authorization Policy Bypass Due to Case Insensitive Host Comparison

Authorization Policy Bypass Due to Case Insensitive Host Comparison

Istio is an open source platform for providing a uniform way to integrate microservices, manage traffic flow across microservices, enforce policies and aggregate telemetry data. According to [RFC 4343](https://datatracker.ietf.org/doc/html/rfc4343), Istio authorization policy should compare the hostname in the HTTP Host header in a case insensitive way, but currently the comparison is case sensitive. The proxy will route the request hostname in a case-insensitive way which means the authorization policy could be bypassed. As an example, the user may have an authorization policy that rejects request with hostname "httpbin.foo" for some source IPs, but the attacker can bypass this by sending the request with hostname "Httpbin.Foo". Patches are available in Istio 1.11.1, Istio 1.10.4 and Istio 1.9.8. As a work around a Lua filter may be written to normalize Host header before the authorization check. This is similar to the Path normalization presented in the [Security Best Practices](https://istio.io/latest/docs/ops/best-practices/security/#case-normalization) guide.

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

大小写敏感处理不恰当

Istio 安全漏洞

Istio是一套连接、管理和保护微服务的开放平台。 Istio 中存在安全漏洞，该漏洞允许攻击者绕过在规则中使用主机的Istio授权策略，从而可能获得对下游服务的访问权。

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