Python DnsApplication · Debian
CVE-2008-4126
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 · uneditedPyDNS (aka python-dns) before 2.3.1-5 in Debian GNU/Linux does not use random source ports for DNS requests and does not use random transaction IDs for DNS retries, which makes it easier for remote attackers to spoof DNS responses, a different vulnerability than CVE-2008-1447. NOTE: this vulnerability exists because of an incomplete fix for CVE-2008-4099.
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 confidencePyDNS (python-dns) before version 2.3.1-5 fails to use random source ports for outgoing DNS requests and does not use random transaction IDs when retrying DNS queries. This allows remote attackers to more easily spoof DNS responses by predicting the source port and transaction ID, enabling DNS cache poisoning attacks.
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
Python DnsApplication
<= 2.3.1-4= 2.3.0-1= 2.3.0-2= 2.3.0-3= 2.3.0-4= 2.3.0-5= 2.3.0-5.1= 2.3.0-6= 2.3.1-1= 2.3.1-2= 2.3.1-3CVSS 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
- 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 PyDNS is installedRun `pip show python-dns` or `dpkg -l | grep python-dns` or `rpm -qa | grep python-dns` depending on your package managerAffected if Package is installed and present in the system
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Determine installed PyDNS versionRun `pip show python-dns | grep Version` or check the package version via your package managerAffected if Version is 2.3.1-4 or earlier, or matches one of these: 2.3.0-1, 2.3.0-2, 2.3.0-3, 2.3.0-4, 2.3.0-5, 2.3.0-5.1, 2.3.0-6, 2.3.1-1, 2.3.1-2, 2.3.1-3
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Check Python code importing PyDNSSearch for `import DNS` or `from py dns import DNS` in your application source codeAffected if Code imports the vulnerable PyDNS module and makes DNS queries using it
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Inspect DNS query behaviorCapture network traffic while the application makes DNS queries and verify if source ports are sequential or fixed rather than randomizedAffected if Source ports are not randomized between queries, indicating the vulnerability is present
You are affected if PyDNS version 2.3.1-4 or any of the specific affected versions (2.3.0-x through 2.3.1-3) is installed and used to perform DNS queries.
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 PyDNS to version 2.3.1-5 or later which implements random source ports and random transaction IDs for DNS retries. If unable to upgrade, consider using a DNS resolver that implements source port randomization.
Fix this in Python Dns
Scoped from the published advisory
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2008-4126 — 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-2008-4126 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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