iOSOperating system · Cisco
CVE-2009-2870
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 · uneditedUnspecified vulnerability in Cisco IOS 12.2 through 12.4, when the Cisco Unified Border Element feature is enabled, allows remote attackers to cause a denial of service (device reload) via crafted SIP messages, aka Bug ID CSCsx25880.
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 confidenceA vulnerability in Cisco IOS 12.2 through 12.4 allows remote attackers to cause device reload via crafted SIP messages when the Cisco Unified Border Element (CUBE) feature is enabled. The vulnerability is in the SIP handling component and can be exploited without authentication.
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
= 12.3yk= 12.3ys= 12.3yt= 12.4gc= 12.4mr= 12.4t= 12.4xa= 12.4xc= 12.4xd= 12.4xe= 12.4xl= 12.4xmCVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:L/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 installed Cisco IOS versionExecute the command 'show version' on the device and locate the version string in the output (typically in the first line, for example: Cisco IOS Software, 12.4XM)Affected if The displayed version matches any of these: 12.3YK, 12.3YS, 12.3YT, 12.4GC, 12.4MR, 12.4T, 12.4XA, 12.4XC, 12.4XD, 12.4XE, 12.4XL, 12.4XM
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Verify if Cisco Unified Border Element is enabledExecute the command 'show running-config | include unified border' or review the running configuration for 'dial-peer voice' entries configured for SIP and 'voice class sip' configurations that indicate CUBE is activeAffected if The device configuration contains CUBE-related SIP dial-peers or voice class sip configurations indicating CUBE is enabled
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Confirm SIP protocol handling is activeExecute 'show sip-ua status' or 'show call active voice' to check if SIP User Agent is configured and handling SIP callsAffected if SIP UA is enabled and the device is configured to process SIP traffic (typically indicated by 'SIP UA' in the output or active SIP calls)
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Check for existing SIP vulnerability symptomsReview logs with 'show logging' and look for patterns indicating SIP-induced reloads or crashes, or check 'show process cpu history' for unusual spikes correlated with SIP trafficAffected if Logs show unexpected reloads or crashes occurring after SIP traffic processing, or CPU spikes during SIP call handling
The environment is affected if the device runs any of the listed IOS versions (12.3YK through 12.4XM) AND has Cisco Unified Border Element with SIP handling enabled, making it vulnerable to remote reload via crafted SIP messages.
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 IOS to a version beyond 12.4 that includes the fix for Bug ID CSCsx25880, or disable the Cisco Unified Border Element feature if upgrade is not immediately feasible.
Fix this in iOS
Scoped from the published advisory
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-2870 — 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-2009-2870 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
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