iOSOperating system · Cisco
CVE-2017-6624
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 Cisco IOS 15.5(3)M Software for Cisco CallManager Express (CME) could allow an unauthenticated, remote attacker to make unauthorized phone calls. The vulnerability is due to a configuration restriction in the toll-fraud protections component of the affected software. An attacker could exploit this vulnerability to place unauthorized, long-distance phone calls by using an affected system. Cisco Bug IDs: CSCuy40939.
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 confidenceA configuration restriction bypass in Cisco CallManager Express (CME) toll-fraud protections allows an unauthenticated, remote attacker to place unauthorized long-distance phone calls. The vulnerability affects Cisco IOS 15.5(3)M in the toll-fraud component.
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
iOSOperating system
= 15.5\(3\)mCVSS 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
- Low
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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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Identify Cisco IOS versionRun 'show version' on the Cisco device CLI to obtain the installed IOS version numberAffected if The displayed version is exactly 15.5(3)M (case-sensitive)
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Confirm CallManager Express is enabledRun 'show telephony-service' or 'show ccm-manager' to check if CME is active on the deviceAffected if CME is running and the device is acting as a CME server
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Verify toll-fraud protection is configuredRun 'show run | include fraud' or 'show telephony-service fraud' to inspect toll-fraud protection settingsAffected if Toll-fraud protections are defined in the CME configuration
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Inspect dial-peer configurations for bypass vectorsRun 'show dial-peer voice' to examine outbound dial-peers and their permission settings, particularly those allowing external/H.323 connectionsAffected if Any dial-peer configurations exist that route to PSTN or external trunks without proper restriction flags
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Check for unrestricted incoming call routingRun 'show telephony-service incoming' to review how incoming calls from external sources are handledAffected if Incoming calls from external SIP or H.323 gateways are routed to extensions without authentication or restriction
You are affected if the device runs Cisco IOS 15.5(3)M with CME enabled and has toll-fraud protection configurations that could be bypassed for unauthorized outbound calling.
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 dataApply proper toll-fraud configuration restrictions in CME and ensure the system is patched to the latest Cisco IOS version. Review and harden dial-plan and call routing configurations to prevent unauthorized outbound calling.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation4.0 h
- Testing3.0 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 $3,728.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-6624 — 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-2017-6624 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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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.
- 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
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