CVE-2021-32747: Icinga Web 2 is an open source monitoring web interface, framework, and command-line interface. A vulnerability in which custom variables are exposed ...

Description

Icinga Web 2 is an open source monitoring web interface, framework, and command-line interface. A vulnerability in which custom variables are exposed to unauthorized users exists between versions 2.0.0 and 2.8.2. Custom variables are user-defined keys and values on configuration objects in Icinga 2. These are commonly used to reference secrets in other configurations such as check commands to be able to authenticate with a service being checked. Icinga Web 2 displays these custom variables to logged in users with access to said hosts or services. In order to protect the secrets from being visible to anyone, it's possible to setup protection rules and blacklists in a user's role. Protection rules result in `***` being shown instead of the original value, the key will remain. Backlists will hide a custom variable entirely from the user. Besides using the UI, custom variables can also be accessed differently by using an undocumented URL parameter. By adding a parameter to the affected routes, Icinga Web 2 will show these columns additionally in the respective list. This parameter is also respected when exporting to JSON or CSV. Protection rules and blacklists however have no effect in this case. Custom variables are shown as-is in the result. The issue has been fixed in the 2.9.0, 2.8.3, and 2.7.5 releases. As a workaround, one may set up a restriction to hide hosts and services with the custom variable in question.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.38%

68.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Icinga	Icinga	>= 2.0.0, < 2.7.5
Icinga	Icinga	>= 2.8.0, < 2.8.3

References

https://github.com/Icinga/icingaweb2/releases/tag/v2.7.5Release Notes, Third Party Advisory
https://github.com/Icinga/icingaweb2/releases/tag/v2.8.3Release Notes, Third Party Advisory
https://github.com/Icinga/icingaweb2/releases/tag/v2.9.0Release Notes, Third Party Advisory
https://github.com/Icinga/icingaweb2/security/advisories/GHSA-2xv9-886q-p7xxExploit, Third Party Advisory
https://github.com/Icinga/icingaweb2/releases/tag/v2.7.5Release Notes, Third Party Advisory
https://github.com/Icinga/icingaweb2/releases/tag/v2.8.3Release Notes, Third Party Advisory
https://github.com/Icinga/icingaweb2/releases/tag/v2.9.0Release Notes, Third Party Advisory
https://github.com/Icinga/icingaweb2/security/advisories/GHSA-2xv9-886q-p7xxExploit, Third Party Advisory

Timeline

Published: Jul 12, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-32747?

Icinga Web 2 is an open source monitoring web interface, framework, and command-line interface. A vulnerability in which custom variables are exposed to unauthorized users exists between versions 2.0.0 and 2.8.2. Custom variables are user-defined keys and values on configuration objects in Icinga 2. These are commonly used to reference secrets in other configurations such as check commands to be able to authenticate with a service being checked. Icinga Web 2 displays these custom variables to logged in users with access to said hosts or services. In order to protect the secrets from being visible to anyone, it's possible to setup protection rules and blacklists in a user's role. Protection rules result in `***` being shown instead of the original value, the key will remain. Backlists will hide a custom variable entirely from the user. Besides using the UI, custom variables can also be accessed differently by using an undocumented URL parameter. By adding a parameter to the affected routes, Icinga Web 2 will show these columns additionally in the respective list. This parameter is also respected when exporting to JSON or CSV. Protection rules and blacklists however have no effect in this case. Custom variables are shown as-is in the result. The issue has been fixed in the 2.9.0, 2.8.3, and 2.7.5 releases. As a workaround, one may set up a restriction to hide hosts and services with the custom variable in question.

How severe is CVE-2021-32747?

CVE-2021-32747 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.38% probability of exploitation in the next 30 days.

How do I fix CVE-2021-32747?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.