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CVE-2021-32747

Custom variable protection and blacklists can be circumvented

5.3 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

1.38%Up 0.3 points since Jul 13, 2021
90%50%10%1%

What each source reports

CVE List Score used 5.3

Custom variable protection and blacklists can be circumvented

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.

Record
CVE-2021-32747
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02
EUVDEUVD-2021-19519 5.3

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.

Record
EUVD-2021-19519
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-03
NVD 5.3

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.

Record
CVE-2021-32747
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS 2.0
4.0 MediumAV:N/AC:L/Au:S/C:P/I:N/A:N
Weakness
CWE-200
Updated
2026-11-02
OSVALPINE-CVE-2021-32747 6.5

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.

Record
ALPINE-CVE-2021-32747
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-03
OSV 6.5

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.

Record
CVE-2021-32747
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2021-32747 6.5

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.

Record
DEBIAN-CVE-2021-32747
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2021-32747 5.3

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.

Record
UBUNTU-CVE-2021-32747
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
icingaweb2
Alpine:v3.15
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.16
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.17
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.18
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.19
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.20
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.21
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.22
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.23
before 2.9.0-r0
2.9.0-r0
icingaweb2
Alpine:v3.24
before 2.9.0-r0
2.9.0-r0
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Affected packages
PackageAffectedFixed
icingaweb2
Debian:12
before 2.8.4-1
2.8.4-1
icingaweb2
Debian:13
before 2.8.4-1
2.8.4-1
icingaweb2
Debian:14
before 2.8.4-1
2.8.4-1
icingaweb2
Ubuntu:16.04:LTS
All versions, plus listed versions
2.1.0-1ubuntu12.1.0-1ubuntu1.12.1.0-1ubuntu1.2
None known
icingaweb2
Ubuntu:18.04:LTS
All versions, plus listed versions
2.4.1-12.4.1-1ubuntu0.1
None known
icingaweb2
Ubuntu:20.04:LTS
All versions, plus listed versions
2.7.1-12.7.3-1
None known
icingaweb2
Ubuntu:22.04:LTS
All versions, plus listed versions
2.8.2-22.9.3-12.9.4-12.9.5-1
None known
icingaweb2
Ubuntu:24.04:LTS
All versions, plus listed versions
2.11.4-32.12.0-12.12.1-1
None known
icingaweb2
Ubuntu:25.10
All versions, plus listed versions
2.12.2-12.12.4-12.12.4-2
None known
icingaweb2
Ubuntu:26.10
All versions, plus listed versions
2.12.6-12.13.0-12.14.0-1
None known
icingaweb2
Ubuntu:26.04:LTS
All versions, plus listed versions
2.12.4-22.12.5-12.12.6-1
None known

History

History
RecordedChangedSources
affected, aliases, referencesOSV
aliasesEUVD
first indexedCVE List, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-32747 is a medium vulnerability (CVSS 5.3) in Icinga, published July 12, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.38%, the 72nd percentile. Fixed in icingaweb2 2.9.0-r0.

References

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