Debian LinuxOperating system · Debian
CVE-2019-25033
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 · uneditedUnbound before 1.9.5 allows an integer overflow in the regional allocator via the ALIGN_UP macro. NOTE: The vendor disputes that this is a vulnerability. Although the code may be vulnerable, a running Unbound installation cannot be remotely or locally exploited
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 confidenceUnbound before version 1.9.5 contains an integer overflow vulnerability in the regional memory allocator's ALIGN_UP macro. This could potentially allow memory corruption or unexpected behavior during memory allocation operations. The vendor disputes the exploitability, claiming no remote or local attack vector exists in practice.
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
= 9.0< 1.9.5CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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 Unbound DNS resolver is installedRun 'unbound -V' or 'unbound-control version' to check if Unbound is present on the system and retrieve its version numberAffected if Unbound is installed and the reported version is lower than 1.9.5
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Verify the exact version numberCompare the installed version against the affected range: any version before 1.9.5 (such as 1.9.4, 1.9.3, 1.9.2, etc.) is within the affected rangeAffected if Installed version is less than 1.9.5 (for example, 1.9.4, 1.9.3, 1.8.x, 1.7.x, or earlier)
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Confirm the regional memory allocator is in useUnbound uses its regional memory allocator by default for internal memory management; this is a core component and is active during normal DNS resolution operationsAffected if Unbound is running and performing DNS queries, as the ALIGN_UP macro is invoked during memory allocation operations in the regional allocator
You are affected if Unbound is installed with a version lower than 1.9.5 and is actively running DNS resolution operations that trigger the regional memory allocator.
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.
dbcve · scoped1.9.5
Upgrade Unbound to version 1.9.5 or later to address the integer overflow in the ALIGN_UP macro. If upgrading is not immediately feasible, monitor for any subsequent security advisories from the vendor.
Unbound >= 1.9.5 (or Debian 10+ with patched unbound package)
- Check current Unbound version with: unbound -V or dpkg -l | grep unbound
- Update package repository lists: apt update
- Upgrade Unbound to version 1.9.5 or later: apt install unbound>=1.9.5
- Verify the installed version: unbound -V
- Restart the Unbound service if running: systemctl restart unbound
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
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-25033 — 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-2019-25033 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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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.
- 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
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