CVE-2011-3581
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 before 1.6.11 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a Resource Record (RR) with an unknown type containing input that is longer than a specified length.
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 the ldns_rr_new_frm_str_internal function in ldns library versions before 1.6.11 allows remote attackers to cause denial of service and potentially execute arbitrary code via specially crafted DNS Resource Records with unknown types containing input longer than the specified length.
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<= 1.6.10= 0.50= 0.60= 0.65= 0.66= 0.70= 1.0.0= 1.1.0= 1.2.0= 1.2.1= 1.2.2= 1.3CVSS 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
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:M/Au:N/C:P/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 installedOn RHEL/CentOS: rpm -qa | grep -i ldns. On Debian/Ubuntu: dpkg -l | grep -i ldns. Or search for libldns files: find /usr -name 'libldns*' 2>/dev/nullAffected if No ldns package or library file is found, meaning the library is not present on the system
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Determine installed ldns versionIf package manager available: rpm -q ldns (RHEL) or dpkg -s ldns (Debian). If library present: ldns-version -v (if installed) or check library file version with strings or readelfAffected if The installed version matches any of these: 0.50, 0.60, 0.65, 0.66, 0.70, 1.0.0, 1.1.0, 1.2.0, 1.2.1, 1.2.2, 1.3, or any version 1.6.10 or earlier
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Identify applications using ldnsRun ldd on common ldns tools if present: ldd $(which drill) 2>/dev/null | grep ldns. Also check: ldd $(which ldns-*.1 2>/dev/null) 2>/dev/null | grep ldnsAffected if Any DNS tool (drill, ldns-verify-zone, etc.) is linked against libldns and processes external DNS data
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Check for active DNS processing servicesLook for services or tools that use ldns for DNS parsing: ps aux | grep -E 'drill|ldns|bind' | grep -v grep. Check if any custom DNS monitoring or validation scripts exist in /usr/local/bin or similarAffected if Any service or script actively parses DNS Resource Records using the ldns library, especially from untrusted network sources
The system is affected if ldns library is installed with a version <= 1.6.10 or matching one of the listed affected versions, AND any application or service uses ldns to parse DNS data from untrusted sources.
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 dataUpgrade ldns library to version 1.6.11 or later. If immediate upgrade is not feasible, implement input validation and strict length checking on DNS RR data before passing to the parsing function, and restrict network exposure of affected systems.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-3581 — 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-2011-3581 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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