CVE-2011-2500
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 · uneditedThe host_reliable_addrinfo function in support/export/hostname.c in nfs-utils before 1.2.4 does not properly use DNS to verify access to NFS exports, which allows remote attackers to mount filesystems by establishing crafted DNS A and PTR records.
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 confidenceThe host_reliable_addrinfo function in nfs-utils before 1.2.4 fails to properly validate DNS records when checking access to NFS exports. An attacker can craft malicious DNS A and PTR records to bypass the access verification mechanism, allowing unauthorized mounting of NFS filesystems.
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<= 1.2.3= 1.2.0= 1.2.1= 1.2.2CVSS 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
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/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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Identify installed nfs-utils versionRun 'rpm -q nfs-utils' (RHEL/CentOS) or 'dpkg -l nfs-utils' (Debian/Ubuntu) to see the installed version. Alternatively, check /usr/sbin/rpc.nfsd or /sbin/mountd version with 'nfsd --version' or 'rpc.nfsd --version'.Affected if The version displayed is 1.2.3 or lower (1.2.0, 1.2.1, 1.2.2) or the package is missing a version string indicating an older release.
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Verify NFS server is configured and runningCheck if /etc/exports exists and contains exported directories. Also run 'exportfs -v' to list active exports and 'rpcinfo -p' to confirm nfsd and mountd services are registered.Affected if NFS exports are defined in /etc/exports or shown by exportfs -v, meaning the system is acting as an NFS server.
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Confirm DNS-based host verification is in useReview /etc/exports entries for hostnames (domain names) rather than IP addresses or CIDR blocks. Entries using hostnames like 'client.example.com' or '*.example.com' rely on DNS resolution for access control. Also check for 'insecure' options or missing IP-specific restrictions.Affected if The /etc/exports file contains hostname-based rules (not IP/CIDR only) that depend on DNS A and PTR record lookups to validate client connections.
You are affected if nfs-utils version 1.2.3 or lower is installed AND the system exports NFS shares using hostname-based access control that relies on DNS resolution.
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 nfs-utils to version 1.2.4 or later. As a defensive measure, use strict IP-based access controls in /etc/exports and implement DNSSEC for DNS validation to ensure record authenticity.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2011-2500 — 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-2011-2500 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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- Version or environment caveats, and links to real fixes
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