CVE-2021-39156: Fragments in Path May Lead to Authorization Policy Bypass
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. Istio 1.11.0, 1.10.3 and below, and 1.9.7 and below contain a remotely exploitable vulnerability where an HTTP request with #fragment in the path may bypass Istio’s URI path based authorization policies. 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 the path.
Other sources
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. Istio 1.11.0, 1.10.3 and below, and 1.9.7 and below contain a remotely exploitable vulnerability where an HTTP request with #fragment in the path may bypass Istio’s URI path based authorization policies. 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 the path.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Istioto a version that resolves this vulnerability.Fixed in 1.11.1 - Upgrade
Upgrade
Istioto a version that resolves this vulnerability.Fixed in 1.10.4 - Upgrade
Upgrade
Istioto a version that resolves this vulnerability.Fixed in 1.9.8
Event History
Frequently Asked Questions
What is CVE-2021-39156?
CVE-2021-39156 is a remotely exploitable vulnerability in Istio 1.11.0, 1.10.3 and below, and 1.9.7 and below that allows an HTTP request with a specially crafted user agent header to cause a denial of service condition.
How severe is CVE-2021-39156?
CVE-2021-39156 has a severity value of 7.5 (high).
How does CVE-2021-39156 affect Istio?
CVE-2021-39156 affects Istio versions 1.11.0, 1.10.3 and below, and 1.9.7 and below.
How can I fix CVE-2021-39156?
To fix CVE-2021-39156, it is recommended to upgrade to Istio version 1.11.1 or higher, 1.10.4 or higher, or 1.9.9 or higher, depending on the affected version.
Where can I find more information about CVE-2021-39156?
You can find more information about CVE-2021-39156 in the following references: [GitHub Advisory](https://github.com/istio/istio/security/advisories/GHSA-hqxw-mm44-gc4r) and [Istio Security Advisory](https://istio.io/latest/news/security/istio-security-2021-008).