CVE-2021-39156 - CVE House

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Status published High CVE-2021-39156

Fragments in Path May Lead to Authorization Policy Bypass

8.1 CVSS

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

istio

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Affected Software

istio

Vulnerable Versions:

< 1.9.8, >= 1.10.0, < 1.10.4, >= 1.11.0, < 1.11.1

Timeline

Official Publish: August 24th, 2021

Last Modified: August 4th, 2024

Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Weaknesses (CWE)

MITRE ATT&CK TTPs

T1190 Exploit Public-Facing Application

T1078 Valid Accounts

T1548 Abuse Elevation Control Mechanism

Privilege Escalation

T1021 Remote Services

Lateral Movement

T1098 Account Manipulation

Defense Evasion