CVE-2011-2216
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 · uneditedreqresp_parser.c in the SIP channel driver in Asterisk Open Source 1.8.x before 1.8.4.2 does not initialize certain strings, which allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a malformed Contact header.
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 SIP channel driver in Asterisk Open Source 1.8.x before 1.8.4.2 contains a vulnerability in reqresp_parser.c where certain strings are not initialized before use. When processing a malformed Contact header in a SIP message, this leads to NULL pointer dereference, causing the Asterisk daemon to crash and resulting in denial of service.
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= 1.8.0= 1.8.1= 1.8.1.1= 1.8.1.2= 1.8.2= 1.8.2.1= 1.8.2.2= 1.8.2.3= 1.8.2.4= 1.8.3= 1.8.3.1= 1.8.3.2CVSS 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
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/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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Determine Asterisk versionRun 'asterisk -V' or 'asterisk --version' from the command line to display the installed Asterisk versionAffected if The version displayed is 1.8.0, 1.8.1, 1.8.1.1, 1.8.1.2, 1.8.2, 1.8.2.1, 1.8.2.2, 1.8.2.3, 1.8.2.4, 1.8.3, 1.8.3.1, or 1.8.3.2
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Verify SIP channel driver is loadedRun 'module show like chan_sip' from the Asterisk CLI to confirm the SIP channel driver module (chan_sip.so) is loadedAffected if The SIP channel driver is loaded and active, making the vulnerability reachable
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Inspect for crash logsCheck /var/log/asterisk/messages or /var/log/asterisk/full for recent crash entries, segmentation faults, or NULL pointer errors around the time of SIP message processingAffected if Recent crashes are logged with NULL pointer dereference errors in the SIP processing path
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Review SIP configurationRun 'sip show settings' from the Asterisk CLI to display current SIP configuration and confirm the SIP peer or user receiving traffic is configuredAffected if SIP peers or users are configured and able to receive SIP messages, which could trigger the malformed Contact header
You are affected if Asterisk version 1.8.0 through 1.8.3.2 is installed, the SIP channel driver is loaded, and the system is configured to process SIP traffic.
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 Asterisk to version 1.8.4.2 or later to obtain the patched version of reqresp_parser.c that properly initializes strings before processing SIP headers.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-2216 — 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-2011-2216 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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