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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.012 (66.3th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 66.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.011 · newest: 0.012 · change: +0.001
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
- github.com/istio/istio/security/advisories/GHSA-hqxw-mm44-gc4r (Third Party Advisory)
- istio.io/latest/news/security/istio-security-2021-008 (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.