Unified Ip Phones 9900 Series FirmwareOperating system · Cisco
CVE-2015-4226
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 packet-storing feature on Cisco 9900 phones with firmware 9.3(2) does not properly support the RTP protocol, which allows remote attackers to cause a denial of service (device hang) by sending malformed RTP packets after a call is answered, aka Bug ID CSCur39976.
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 · moderate confidenceCisco 9900 phones with firmware 9.3(2) contain a vulnerability in the packet-storing feature where improper RTP protocol handling allows remote attackers to send malformed RTP packets after a call is answered, causing the device to hang 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
Unified Ip Phones 9900 Series FirmwareOperating system
= 9.3\(2\)CVSS 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
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:M/Au:N/C:N/I:N/A:C
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 the exact firmware versionAccess the phone's web interface or use the Cisco Unified Communications Manager device page to retrieve the firmware version. On the physical phone, navigate to Settings > Device Information > Firmware Version or similar path depending on phone model.Affected if Firmware version is exactly 9.3(2)
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Confirm the device modelCheck that the device is a Cisco Unified IP Phone 9900 Series (9911, 9921, or related models) by examining the device label, web interface, or the Cisco Unified Communications Manager device inventory.Affected if Device is a Cisco 9900 series IP phone and firmware is 9.3(2)
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Determine if RTP traffic is processedVerify that the phone is configured to handle real-time transport protocol (RTP) streams, which is required for VoIP call functionality. Check if the phone has active call handling capability or is registered with a call control system like Cisco Unified Communications Manager.Affected if Phone processes RTP packets and firmware is 9.3(2)
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Assess network accessibilityReview network segmentation and access controls around the phone. Determine if the phone is on a restricted VLAN or behind a firewall that limits who can send RTP packets to the device. Use network scanning or access logs to identify reachable IP addresses.Affected if Phone is network-accessible to untrusted parties and firmware is 9.3(2)
A user is affected if they have a Cisco 9900 Series IP Phone running firmware exactly version 9.3(2) that processes RTP traffic and is accessible to network attackers.
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 Cisco 9900 phones to a firmware version beyond 9.3(2) that addresses CSCur39976; as an interim control, restrict unauthorized network access to phones and implement RTP traffic monitoring to detect malformed packets.
Fix this in Unified Ip Phones 9900 Series Firmware
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-4226 — 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-2015-4226 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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