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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.


Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 8.1, indicating it can be exploited remotely over the network with relatively low complexity though user interaction is required and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), for affected systems. Impacting 1 product from istio organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-08-24T23:15:10.413

Last Modified

2024-11-21T06:18:44.510

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 8.1 (HIGH)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:P/I:N/A:N

  • Access Vector: NETWORK
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: PARTIAL
  • Integrity Impact: NONE
  • Availability Impact: NONE
Exploitability Score

10.0

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-863
  • Type: Primary
    CWE-706

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application istio istio < 1.9.8 Yes
Application istio istio < 1.10.3 Yes
Application istio istio < 1.11.1 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For istio's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.