CVE-2026-42390
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 · uneditedAn invalid zone might pass ZONEMD validation while it should not. This is only relevant if ZoneToCache is configured with ZONEMD validation.
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 · moderate confidenceZONEMD (zone message digest) validation in ZoneToCache contains a logic flaw that allows invalid zones to pass integrity checks when they should be rejected. This is a validation bypass where the cryptographic verification incorrectly returns success for zones that fail proper validation criteria.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify if ZoneToCache is deployedSearch for ZoneToCache binaries, processes, or configuration files in your environment. Check for any custom DNS or zone management tools that may incorporate ZoneToCache functionality.Affected if ZoneToCache is present in the environment and performs ZONEMD validation on zone data.
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Locate ZoneToCache configurationLook for configuration files (commonly named zonemd.conf, zone.conf, or similar) or command-line arguments that specify ZONEMD validation options. Check process listings or startup scripts for ZoneToCache invocations.Affected if ZONEMD validation is explicitly configured or enabled as a validation option.
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Confirm ZONEMD validation is activeExamine runtime configuration or logs for ZONEMD-related directives such as 'validate-zonemd', 'zonemd-check', or equivalent. Verify whether the feature flag or config option for ZONEMD is set to 'enabled' or 'true'.Affected if ZONEMD validation is actively used to verify zone integrity at runtime.
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Check for zone ingestion behaviorMonitor or review logs for zone import/transfer operations where ZoneToCache processes incoming zone data. Look for entries indicating ZONEMD verification is performed during zone loading.Affected if ZoneToCache is actively processing and validating zones with ZONEMD enabled.
If ZoneToCache is in use with ZONEMD validation enabled for processing zone data, the environment is potentially affected by this validation bypass flaw.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataApply the vendor patch when available. Until then, evaluate whether ZoneToCache with ZONEMD validation is mission-critical; consider disabling ZONEMD validation or avoiding ZoneToCache for affected deployments.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-42390 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-42390 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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