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iOSOperating system · Cisco

CVE-2009-5039

MEDIUM · 5.0 CVSS v2.0 Published 2011-01-07
Fix available
A fix is available. Upgrade to 15.0 or later.
See remediation →
59/100
Remediation priority · Elevated
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
Memory leak in the gk_circuit_info_do_in_acf function in the H.323 implementation in Cisco IOS before 15.0(1)XA allows remote attackers to cause a denial of service (memory consumption) via a large number of calls over a long duration, as demonstrated by InterZone Clear Token (IZCT) test traffic, aka Bug ID CSCsz72535.

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

Memory leak in the gk_circuit_info_do_in_acf function in Cisco IOS H.323 implementation allows remote attackers to cause denial of service through sustained high-volume call traffic, leading to memory exhaustion over time.

MitigationUpgrade Cisco IOS to version 15.0(1)XA or later which contains the fix for this vulnerability.

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
Affected:< 15.0\(1\)xa

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
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

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 the device OS and version
    Run 'show version' command on the Cisco device to obtain the IOS version number
    Affected if The device is running Cisco IOS with a version earlier than 15.0(1)XA
  2. Confirm H.323 is enabled
    Run 'show h323' or 'show running-config | include h323' to check if H.323 protocol support is configured
    Affected if H.323 is actively enabled on the device
  3. Verify the specific vulnerability function
    Check for the gk_circuit_info_do_in_acf function in the IOS image by examining H.323 gatekeeper configuration with 'show gatekeeper circuit'
    Affected if H.323 gatekeeper circuit functionality is present and active

The device is affected if it runs Cisco IOS version below 15.0(1)XA with H.323 protocol enabled, as the memory leak in the gk_circuit_info_do_in_acf function can be triggered by sustained high-volume call traffic.

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
Upgrade available Upgrade to 15.0 or later
Fixed in 15.0
Interim mitigation

Upgrade Cisco IOS to version 15.0(1)XA or later which contains the fix for this vulnerability.

Fix this in iOS Scoped from the published advisory
  • Consultation6.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,760.

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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-2009-5039 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