dbcve.org
Unified Communications ManagerApplication · Cisco

CVE-2024-20375

HIGH · 7.5 CVSS v3.1 Published 2024-08-21
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 SIP call processing function of Cisco Unified Communications Manager (Unified CM) and Cisco Unified Communications Manager Session Management Edition (Unified CM SME) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper parsing of SIP messages. An attacker could exploit this vulnerability by sending a crafted SIP message to an affected Cisco Unified CM or Cisco Unified CM SME device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition that interrupts the communications of reliant voice and video devices.

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

A denial of service vulnerability exists in the SIP call processing function of Cisco Unified Communications Manager and Unified CM SME due to improper parsing of SIP messages. An unauthenticated remote attacker can send specially crafted SIP messages that cause the affected device to reload, disrupting voice and video communications for all reliant devices.

MitigationApply the vendor-supplied patch for CVE-2024-20375 when available. As an interim measure, implement network-level filtering (ACLs or firewall rules) to restrict SIP traffic from untrusted sources to reduce exploitability, while ensuring legitimate SIP communications remain functional.

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:= 12.0\(1\)su1= 12.0\(1\)su2= 12.0\(1\)su3= 12.0\(1\)su4= 12.0\(1\)su5= 12.5\(1\)= 12.5\(1\)su1= 12.5\(1\)su2= 12.5\(1\)su3= 12.5\(1\)su4= 12.5\(1\)su5= 12.5\(1\)su6

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:3.1/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. Check CUCM version
    Log into the Cisco Unified Communications Manager CLI and run 'show version' or access the Cisco Unified Communications Operating System GUI and navigate to Show License Usage to view the installed version.
    Affected if The installed version matches 12.0(1)su1 through 12.0(1)su5 or 12.5(1) through 12.5(1)su6.
  2. Confirm SIP service is enabled
    Navigate to Cisco Unified Serviceability > Service Activation or use the CLI command 'show service' to verify that the Cisco SIP Proxy service is activated.
    Affected if SIP Proxy service is running or enabled on the affected CUCM node.
  3. Check for SIP trunk configurations
    In CUCM Administration, go to System > Trunk Configuration and review all configured trunks. Alternatively, use the CLI command 'show sip trunk summary' to list active SIP trunks.
    Affected if Any SIP trunks are configured and active, indicating SIP is in use.
  4. Inspect SIP message handling logs
    Enable detailed SIP logging via Cisco Unified Serviceability > Trace > Configuration, then review the SIP logs (specifically the sipImAndProxyLog) for anomalies or parsing errors related to incoming SIP messages.
    Affected if Large volumes of incoming SIP traffic are logged, especially from untrusted sources.

You are affected if you run a vulnerable CUCM version (12.0(1)su1-su5 or 12.5(1)-12.5(1)su6) and have SIP service or SIP trunks enabled, exposing the device to specially crafted SIP messages.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-supplied patch for CVE-2024-20375 when available. As an interim measure, implement network-level filtering (ACLs or firewall rules) to restrict SIP traffic from untrusted sources to reduce exploitability, while ensuring legitimate SIP communications remain functional.

Recommended fix Moderate confidence

Cisco Unified Communications Manager 12.0(1) SU5 or later (or migrate to 12.5(1) / 14.x release train for longer support)

  1. 1. Identify the current Cisco Unified Communications Manager version by accessing the Cisco Unified Reporting tool or via CLI: 'show version'
  2. 2. Schedule a maintenance window for the upgrade process
  3. 3. Back up the current Cisco Unified CM configuration using the Disaster Recovery System or backup feature
  4. 4. Download the fixed release (Cisco Unified Communications Manager 12.0(1) SU5 or later) from Cisco Software Central
  5. 5. Install the upgrade following Cisco's standard installation guide for CUCM service updates
  6. 6. After upgrade, verify the SIP service is running: 'utils service list'
  7. 7. Confirm the new version is installed: 'show version'
Caveat Review Cisco's release notes for any compatibility changes; ensure UC applications and endpoints are on supported firmware versions before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Unified Communications Manager Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
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Scan for this in your stack

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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-2024-20375 in production — separate from our analysis above.

No notes yet

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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
  • 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
  • No spam, self-promotion, credentials, or personal data