CVE-2011-4597
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 SIP over UDP implementation in Asterisk Open Source 1.4.x before 1.4.43, 1.6.x before 1.6.2.21, and 1.8.x before 1.8.7.2 uses different port numbers for responses to invalid requests depending on whether a SIP username exists, which allows remote attackers to enumerate usernames via a series of requests.
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 over UDP implementation in Asterisk uses different port numbers for responses to invalid requests depending on whether a SIP username exists in the system, allowing remote attackers to enumerate valid usernames through a series of requests.
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
- Partial
- Integrity
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:N/A:N
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 installed Asterisk versionRun 'asterisk -V' or 'asterisk -x "core show version"' to determine the exact version numberAffected if The version matches 1.8.0 through 1.8.3.2 (any of: 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, 1.8.3.2)
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Verify SIP over UDP is enabledCheck sip.conf (or pjsip.conf for newer versions) for 'transport=udp' or 'udpbindaddr' settings, and confirm the UDP port (typically 5060) is listening via 'netstat -uan | grep 5060' or 'ss -uan | grep 5060'Affected if SIP over UDP transport is configured and the UDP port is open and listening
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Confirm SIP users or extensions existReview sip.conf for [general] user definitions or check 'sip show users' or 'pjsip show endpoints' via the Asterisk CLIAffected if At least one SIP user or endpoint is configured in the system
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Test for username enumeration via port variationSend an invalid SIP request (such as OPTIONS or INVITE) to the Asterisk UDP port targeting a non-existent username, then send the same request targeting a valid username, and compare the source ports of the ICMP unreachable or SIP error responses using a packet capture (tcpdump or Wireshark) or 'ngrep'Affected if The response port numbers differ between valid and invalid usernames, indicating the vulnerability is present
If running Asterisk 1.8.0-1.8.3.2 with SIP over UDP enabled and SIP users configured, and testing confirms different response ports for valid versus invalid usernames, the environment is affected by this username enumeration vulnerability.
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 Asterisk to version 1.4.43, 1.6.2.21, 1.8.7.2 or later to obtain the security patch that standardizes response port handling.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-4597 — 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-2011-4597 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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