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Unified Communications ManagerApplication · Cisco

CVE-2017-6791

HIGH · 7.5 CVSS v3.0 Published 2017-09-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
A vulnerability in the Trust Verification Service (TVS) of Cisco Unified Communications Manager could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper handling of Transport Layer Security (TLS) traffic by the affected software. An attacker could exploit this vulnerability by generating incomplete traffic streams. A successful exploit could allow the attacker to deny access to the TVS for an affected device, resulting in a DoS condition, until an administrator restarts the service. Known Affected Releases 10.0(1.10000.24) 10.5(2.10000.5) 11.0(1.10000.10) 9.1(2.10000.28). Cisco Bug IDs: CSCux21905.

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 confidence

The vulnerability exists in Cisco Unified Communications Manager's Trust Verification Service (TVS), which improperly handles Transport Layer Security (TLS) traffic. An unauthenticated remote attacker can exploit this by generating incomplete traffic streams, causing the TVS to become unresponsive. The DoS condition persists until an administrator manually restarts the service.

MitigationApply the Cisco security patches for CSCux21905 corresponding to the affected release versions (9.1, 10.0, 10.5, 11.0). As a temporary workaround, consider implementing network-level filtering or rate limiting for TLS connections to the TVS until the patch can be applied.

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 Communications ManagerApplication
Affected:= 9.1\(2.10000.28\)= 10.0\(1.10000.24\)= 10.5\(2.10000.5\)= 11.0\(1.10000.10\)

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
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Cisco UCM version
    Log into the Cisco Unified Communications Manager Administration interface and navigate to About > Version, or run 'show version' via CLI on the UCM server
    Affected if The installed version matches 9.1(2.10000.28), 10.0(1.10000.24), 10.5(2.10000.5), or 11.0(1.10000.10)
  2. Verify TVS service is enabled
    In UCM Administration, go to Cisco Unified Serviceability > Service Activation and check if 'Trust Verification Service' is activated for the relevant node
    Affected if Trust Verification Service is activated and running
  3. Confirm TVS is listening on network
    From the UCM server CLI, run 'show network ethernet eth0' or use 'netstat -an | grep' for TVS ports (typically 8443/tcp for TVS HTTPS). Check if the service is bound to an accessible IP address
    Affected if TVS is bound to a routable IP address and accepting connections
  4. Check for DoS symptom
    Attempt to access the TVS endpoint (e.g., via curl or browser to https://<ucm-ip>:8443/tvs) or check service status via CLI command 'utils service list' to see if TVS shows as 'Down' or 'Unresponsive'
    Affected if TVS service is in a Down or Unresponsive state after receiving incomplete TLS traffic

You are affected if your Cisco UCM version matches one of the four specific builds listed AND the Trust Verification Service is enabled and exposed, particularly if the service is currently unresponsive.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco security patches for CSCux21905 corresponding to the affected release versions (9.1, 10.0, 10.5, 11.0). As a temporary workaround, consider implementing network-level filtering or rate limiting for TLS connections to the TVS until the patch can be applied.

Fix this in Unified Communications Manager Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-6791 in production — separate from our analysis above.

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What this is

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.

What belongs here
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  • Version or environment caveats, and links to real fixes
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