VULNERABILITY INTELLIGENCE

CVE-2021-39156

CVSS score8.1 HIGH

EPSS probability1.17%

CISA KEVNot currently listed

Published2021-08-24

Last modified2026-06-17

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

Description

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.

Weakness classification

CWE-706: Use of Incorrectly-Resolved Name or Reference
CWE-863: Incorrect Authorization

Primary references

security-advisories@github.com — Third Party Advisory
security-advisories@github.com — Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108 — Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Vendor Advisory