CVE-2009-1086
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 · uneditedHeap-based buffer overflow in the ldns_rr_new_frm_str_internal function in ldns 1.4.x allows remote attackers to cause a denial of service (memory corruption) and possibly execute arbitrary code via a DNS resource record (RR) with a long (1) class field (clas variable) and possibly (2) TTL field.
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 confidenceHeap-based buffer overflow in ldns_rr_new_frm_str_internal function in ldns 1.4.x allows remote attackers to cause memory corruption and potentially execute arbitrary code via DNS resource records with oversized class (clas) and TTL fields.
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= 1.4.0= 1.4.1CVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:P/A:P
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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Check if ldns library is installedRun 'dpkg -l | grep ldns' on Debian/Ubuntu, or 'rpm -qa | grep ldns' on RedHat/CentOS, or check for libldns files in /usr/lib/Affected if ldns library package is found on the system
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Identify the installed ldns versionRun 'ldns-version' if available, or check the library file with 'ldd --version' or inspect the package version with the package manager commands used in step 1Affected if The installed version is exactly 1.4.0 or 1.4.1
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Identify applications using ldns for DNS parsingSearch for binaries or services that link against libldns: 'ldconfig -p | grep ldns' and review any DNS-related software (like dnssec-tools, drill, ldns-verify-zone, or custom applications)Affected if Applications that parse DNS resource records are linked against the vulnerable ldns library
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Determine if ldns parses untrusted DNS dataReview configuration or logs of ldns-linked applications to determine if they process DNS records from network sources or zone files from untrusted partiesAffected if The ldns library is used to parse DNS resource records from untrusted or network sources
The system is affected only if ldns version 1.4.0 or 1.4.1 is installed AND it is used to parse DNS resource records from untrusted or network sources, as the heap overflow requires parsing oversized class/TTL fields in DNS RR data.
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 dataUpdate ldns to a patched version; alternatively, implement input validation on DNS RR parsing to reject malformed records with oversized class/TTL fields before passing to the vulnerable function.
- Consultation3.0 h
- Implementation6.0 h
- Testing5.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-1086 — 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-2009-1086 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
- No weaponised exploit code, or anything meant to cause harm
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