Secure Access Control SystemApplication · Cisco
CVE-2013-5536
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 · uneditedCisco Secure Access Control System (ACS) does not properly implement an incoming-packet firewall rule, which allows remote attackers to cause a denial of service (process crash) via a flood of crafted packets, aka Bug ID CSCui51521.
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 confidenceCisco Secure Access Control System (ACS) fails to properly implement an incoming-packet firewall rule, allowing remote attackers to crash the ACS process via a flood of crafted packets. The vulnerability stems from missing or inadequate firewall filtering at the system level.
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
Secure Access Control SystemApplication
all versionsCVSS 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 checksWork through these to decide whether this CVE applies to you.
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Confirm Cisco ACS is deployedIdentify whether Cisco Secure Access Control System is installed in your environment. Check for ACS servers, ACS services, or the ACS application in your asset inventory.Affected if Cisco Secure Access Control System is present in the environment
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Verify firewall rules on the ACS systemExamine the local firewall configuration on the ACS server to determine whether incoming packet filtering rules are properly defined and enabled. Look for rules that inspect or limit incoming traffic to the ACS service ports.Affected if No incoming-packet firewall rules exist or rules are disabled, leaving ACS exposed to unauthenticated traffic
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Check network-edge filteringInspect upstream network devices (firewalls, ACLs, IDS/IPS) positioned between the internet and the ACS system to see if they filter or rate-limit suspicious traffic before it reaches ACS.Affected if Network-level filtering is absent or insufficient, allowing crafted packets to reach the ACS system directly
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Look for ACS process crashesReview system logs, event logs, or ACS diagnostic logs for recent instances of the ACS process terminating unexpectedly or entering a failed state.Affected if The ACS process has crashed or restarted unexpectedly without an identifiable cause
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Assess exposure to untrusted networksDetermine whether the ACS management interface or service ports are accessible from untrusted networks, the internet, or external IP addresses without intervening filtering.Affected if ACS is directly reachable from untrusted networks without firewall protection
The environment is affected if Cisco ACS is present AND either no firewall rules exist to filter incoming packets to ACS, or network-edge filtering is missing, allowing external attackers to send crafted traffic directly to the system.
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 Cisco-provided patches for CSCui51521 or implement network-level ACLs/firewall rules to filter suspicious traffic before reaching the ACS system. Consider rate limiting at network perimeter.
Fix this in Secure Access Control System
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 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 $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-5536 — 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-2013-5536 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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