Wide Area Application ServicesApplication · Cisco
CVE-2016-6437
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 the SSL session cache management of Cisco Wide Area Application Services (WAAS) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to high consumption of disk space. The user would see a performance degradation. More Information: CSCva03095. Known Affected Releases: 5.3(5), 6.1(1), 6.2(1). Known Fixed Releases: 5.3(5g)1, 6.2(2.32).
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 the SSL session cache management of Cisco WAAS allows an unauthenticated remote attacker to cause excessive disk space consumption, leading to denial of service. The flaw allows unbounded growth of the SSL session cache, degrading performance.
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
Wide Area Application ServicesApplication
= 5.3.1= 5.3.3= 5.3.5= 5.3.5a= 5.3.5b= 5.3.5c= 5.3.5d= 5.3.5e= 5.3.5f= 6.1.0= 6.1.1= 6.2.1CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:H/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 checksWork through these to decide whether this CVE applies to you.
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Confirm Cisco WAAS installation and versionRun 'show version' command on the WAAS device CLI to identify the installed software versionAffected if The displayed version matches any of these: 5.3.1, 5.3.3, 5.3.5, 5.3.5a, 5.3.5b, 5.3.5c, 5.3.5d, 5.3.5e, 5.3.5f, 6.1.0, 6.1.1, or 6.2.1
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Verify SSL acceleration is enabledCheck WAAS configuration for SSL services using 'show running-config' or 'show ssl' commands to confirm SSL session cache functionality is activeAffected if SSL acceleration or SSL termination is configured and active on the WAAS device
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Monitor disk space consumptionUse 'disk monitor' or 'show disk' commands to check for abnormal disk usage growth over timeAffected if Disk usage is growing unbounded or approaching capacity without reasonable explanation
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Inspect SSL session cache sizeUse 'show ssl statistics' or 'show cache ssl-session' commands to examine the SSL session cache size and entry countAffected if The SSL session cache shows excessive entries or unbounded growth compared to expected values
You are affected if the device runs a matched WAAS version from the affected list AND SSL session handling is enabled, leading to uncontrolled cache growth.
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 WAAS to fixed releases 5.3(5g)1 or 6.2(2.32) or later. Monitor disk usage on WAAS appliances and implement SSL session cache size limits if available.
Fix this in Wide Area Application Services
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-6437 — 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-2016-6437 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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- Version or environment caveats, and links to real fixes
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