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.

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:3273 advisory.

    Red Hat OpenShift Service Mesh is Red Hat's distribution of the Istio service mesh project, tailored for     installation into an on-premise OpenShift Container Platform installation.

    Security Fix(es):

    * envoyproxy/envoy: HTTP request with multiple value headers can bypass authorization policies     (CVE-2021-32777)

    * envoyproxy/envoy: HTTP request with a URL fragment in the URI can bypass authorization policies     (CVE-2021-32779)

    * envoyproxy/envoy: denial of service when using extensions that modify request or response sizes     (CVE-2021-32781)

    * istio/istio: HTTP request can bypass authorization mechanisms due to case insensitive host comparison     (CVE-2021-39155)

    * istio/istio: HTTP request with fragment in URI can bypass authorization mechanisms (CVE-2021-39156)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:3272 advisory.

    Red Hat OpenShift Service Mesh is Red Hat's distribution of the Istio service mesh project, tailored for     installation into an on-premise OpenShift Container Platform installation.

    Security Fix(es):

    * envoyproxy/envoy: HTTP request with multiple value headers can bypass authorization policies     (CVE-2021-32777)

    * envoyproxy/envoy: HTTP request with a URL fragment in the URI can bypass authorization policies     (CVE-2021-32779)

    * envoyproxy/envoy: denial of service when using extensions that modify request or response sizes     (CVE-2021-32781)

    * istio/istio: HTTP request can bypass authorization mechanisms due to case insensitive host comparison     (CVE-2021-39155)

    * istio/istio: HTTP request with fragment in URI can bypass authorization mechanisms (CVE-2021-39156)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
152829	RHEL 8 : Red Hat OpenShift Service Mesh 1.1.17.1 (RHSA-2021:3273)	Nessus	Red Hat Local Security Checks	high
152828	RHEL 8 : Red Hat OpenShift Service Mesh 2.0.7.1 (RHSA-2021:3272)	Nessus	Red Hat Local Security Checks	high

Detections

Analytics

CVE-2021-39155

high

Tenable Plugins

high

high