CVE-2021-39155

Public on

Last Modified: UTC

ImportantImportant ImpactWhat does this mean?
DescriptionAdditional informationCVSS Score DetailsWeakness (CWE)AcknowledgementsFAQ

Description

An authorization bypass vulnerability was found in istio/istio. The case insensitive host comparison incorrectly works when evaluating rules specified with `host` or `notHost`. This flaw allows an attacker to bypass an Istio authorization policy that uses hosts in the rules, potentially gaining access to the downstream services. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

An authorization bypass vulnerability was found in istio/istio. The case insensitive host comparison incorrectly works when evaluating rules specified with host or notHost. This flaw allows an attacker to bypass an Istio authorization policy that uses hosts in the rules, potentially gaining access to the downstream services. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Additional information

  • Bugzilla 1996929: istio/istio: HTTP request can bypass authorization mechanisms due to case insensitive host comparison
  • CWE-863: Incorrect Authorization
  • FAQ: Frequently asked questions about CVE-2021-39155

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

CVSS v3 Score Breakdown
Red HatNVD

CVSS v3 Base Score

8.3

7.5

Attack Vector

Network

Network

Attack Complexity

Low

Low

Privileges Required

None

None

User Interaction

None

None

Scope

Changed

Unchanged

Confidentiality Impact

Low

High

Integrity Impact

Low

None

Availability Impact

Low

None

CVSS v3 Vector

Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L

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

Acknowledgements

Red Hat would like to thank the Istio Product Security Working Group for reporting this issue.

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

What can I do if my product is listed as "Will not fix"?

What can I do if my product is listed as "Fix deferred"?

What is a mitigation?

I have a Red Hat product but it is not in the above list, is it affected?

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

Want to get errata notifications? Sign up here.