Telepresence Video Communication ServerApplication · Cisco
CVE-2019-1721
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 · uneditedA vulnerability in the phone book feature of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an authenticated, remote attacker to cause the CPU to increase to 100% utilization, causing a denial of service (DoS) condition on an affected system. The vulnerability is due to improper handling of the XML input. An attacker could exploit this vulnerability by sending a Session Initiation Protocol (SIP) message with a crafted XML payload to an affected device. A successful exploit could allow the attacker to exhaust CPU resources, resulting in a DoS condition. Manual intervention may be required to recover the device. This vulnerability is fixed in Cisco Expressway Series and Cisco TelePresence Video Communication Server Releases X12.5.1 and later.
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 vulnerability exists in the phone book feature of Cisco Expressway Series and Cisco TelePresence VCS. An authenticated attacker can send a SIP message containing a crafted XML payload to the affected device. Due to improper XML input handling, this causes the CPU to max out at 100%, resulting in denial of service. Manual intervention is required to recover the device.
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
Telepresence Video Communication ServerApplication
< x12.5.1CVSS 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
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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 product and versionAccess the admin web interface or CLI and locate the version information for Cisco Expressway Series or TelePresence VCSAffected if The version is Cisco TelePresence VCS (or Expressway) and is below x12.5.1
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Verify phone book feature is enabledCheck the device configuration settings for the phone book feature status through the admin web interface or CLIAffected if The phone book feature is enabled (this is the vulnerable component)
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Confirm SIP service is runningVerify that the SIP service is active on the device, as this is required to receive the malicious SIP messagesAffected if SIP service is enabled and reachable on the device
The device is affected if it is running Cisco Expressway Series or TelePresence VCS with version below x12.5.1 AND has the phone book feature enabled, as exploitation requires sending a crafted SIP XML message to the phone book endpoint.
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 Expressway Series and TelePresence VCS to release X12.5.1 or later. Until upgrade is possible, restrict access to the phone book feature and monitor for unusual SIP traffic patterns.
Fix this in Telepresence Video Communication Server
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-1721 — 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-2019-1721 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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