Auth bypass in Istio
CVE-2021-39156
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.
Vulnerability class: Broken Access Control
EPSS: 0.011 (62.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.
Affected products
- Istio — versions < 1.9.8, >= 1.10.0, < 1.10.4, >= 1.11.0, < 1.11.1
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (x_refsource_MISC, Vendor Advisory)
Frequently asked questions
- What is CVE-2021-39156?
- CVE-2021-39156 is a high-severity vulnerability in Istio, classified under Incorrect Authorization. CVSS score: 8.1/10. Published 2021-08-24.
- How severe is CVE-2021-39156?
- High severity. CVSS v3 base score is 8.1 out of 10.
- Is CVE-2021-39156 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.