dbcve.org
Debian LinuxOperating system · Debian

CVE-2021-37698

HIGH · 7.5 CVSS v3.1 Published 2021-08-19
Fix available
A fix is available. Upgrade to 2.11.10 / 2.12.6 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Icinga is a monitoring system which checks the availability of network resources, notifies users of outages, and generates performance data for reporting. In versions 2.5.0 through 2.13.0, ElasticsearchWriter, GelfWriter, InfluxdbWriter and Influxdb2Writer do not verify the server's certificate despite a certificate authority being specified. Icinga 2 instances which connect to any of the mentioned time series databases (TSDBs) using TLS over a spoofable infrastructure should immediately upgrade to version 2.13.1, 2.12.6, or 2.11.11 to patch the issue. Such instances should also change the credentials (if any) used by the TSDB writer feature to authenticate against the TSDB. There are no workarounds aside from upgrading.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The ElasticsearchWriter, GelfWriter, InfluxdbWriter, and Influxdb2Writer features in Icinga 2 versions 2.5.0-2.13.0 fail to validate TLS server certificates even when a certificate authority is explicitly configured, enabling man-in-the-middle attacks on networks where traffic can be spoofed or intercepted.

MitigationUpgrade Icinga 2 to version 2.13.1, 2.12.6, or 2.11.11, and rotate credentials used by the affected TSDB writer features.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Debian LinuxOperating system
Affected:= 9.0
IcingaApplication
Affected:>= 2.5.0, < 2.11.10>= 2.12.0, < 2.12.6>= 2.13.0, < 2.13.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Icinga 2 version
    Run 'icinga2 --version' or check the package version using your system package manager (e.g., 'dpkg -l icinga2' on Debian)
    Affected if The installed version is 2.5.0 through 2.13.0 (specifically < 2.11.10, or >= 2.12.0 and < 2.12.6, or >= 2.13.0 and < 2.13.1)
  2. Identify enabled TSDB writer features
    List files in /etc/icinga2/features-enabled/ directory and look for: elasticsearchwriter.conf, gelfwriter.conf, influxdbwriter.conf, influxdb2writer.conf
    Affected if Any of these feature configuration files are present and enabled
  3. Verify TLS configuration in writer features
    Examine the configuration file for each enabled writer (e.g., /etc/icinga2/features-enabled/influxdbwriter.conf) and check if the 'enable_tls' or 'tls' setting is set to 'true' or if a 'ca_file' or 'tls_cert_path' is configured
    Affected if TLS is enabled or a CA is configured for any of the affected writers
  4. Confirm certificate validation behavior
    Review the feature configuration for the 'tls_verify' or 'ssl_verify' parameter. If absent or set to 'false', TLS certificate validation is disabled
    Affected if Certificate verification is disabled or not explicitly set to 'true' for TLS-enabled connections

You are affected if Icinga 2 version is within the vulnerable range AND any of ElasticsearchWriter, GelfWriter, InfluxdbWriter, or Influxdb2Writer features are enabled with TLS configured but certificate validation is not explicitly enforced.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.11.10 / 2.12.6 / 2.13.1 or later
Fixed in 2.11.102.12.62.13.1
Interim mitigation

Upgrade Icinga 2 to version 2.13.1, 2.12.6, or 2.11.11, and rotate credentials used by the affected TSDB writer features.

Recommended fix High confidence

2.13.1 (or 2.12.6/2.11.11 depending on compatibility with existing setup)

  1. 1. Identify which TSDB writer features are enabled in Icinga 2 (ElasticsearchWriter, GelfWriter, InfluxdbWriter, or Influxdb2Writer)
  2. 2. Plan the upgrade to one of the fixed versions: 2.13.1, 2.12.6, or 2.11.11
  3. 3. Backup the Icinga 2 configuration and database before upgrading
  4. 4. Upgrade Icinga 2 to the chosen fixed version using the package manager (apt-get for Debian)
  5. 5. After upgrade, restart the Icinga 2 service
  6. 6. Change the credentials used by the TSDB writer features to authenticate against the time series databases

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-37698 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data