Email Security ApplianceHardware / appliance · Cisco
CVE-2015-6309
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 Email Security Appliance (ESA) 8.5.6-106 and 9.6.0-042 allows remote authenticated users to cause a denial of service (file-descriptor consumption and device reload) via crafted HTTP requests, aka Bug ID CSCuw32211.
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 Email Security Appliance (ESA) versions 8.5.6-106 and 9.6.0-042 contain a denial of service vulnerability where authenticated remote users can send crafted HTTP requests that consume file descriptors and trigger device reload, causing service disruption.
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
Email Security ApplianceHardware / appliance
= 9.6.0-042
Email Security Appliance FirmwareOperating system
= 8.5.6-106CVSS 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
- Single
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:L/Au:S/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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Determine the installed ESA versionLog into the ESA CLI and run the 'version' command, or check the web interface System Administration > Device Management page for the firmware version.Affected if The version displayed is exactly 8.5.6-106 or exactly 9.6.0-042.
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Verify HTTP management interface is enabledCheck the ESA web interface under Network > Interfaces > HTTP Proxy settings, or in the CLI run 'listenerconfig' to see if HTTP is configured for management access.Affected if HTTP management interface is enabled and accessible on any interface.
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Confirm management access exposureReview the network configuration to determine if the ESA HTTP management interface is reachable from untrusted networks. Check the access list or firewall rules permitting HTTP (port 80) or HTTPS (port 443) traffic to the ESA.Affected if HTTP management is exposed to networks beyond trusted administrators.
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Review recent authentication activityCheck ESA logs (Mail Logs > HTTP Logs) for unusual or excessive authentication requests from external or unexpected IP addresses.Affected if Multiple authenticated HTTP requests from non-administrator accounts are observed.
A user is affected if their ESA runs exactly version 8.5.6-106 or 9.6.0-042 AND has HTTP management interface enabled and accessible to authenticated users.
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 the Cisco security update for Bug ID CSCuw32211 to upgrade to a patched ESA version. Until patched, restrict HTTP management access to trusted authenticated users only and monitor for abnormal device behavior.
Fix this in Email Security Appliance
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 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 $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-6309 — 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-2015-6309 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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- 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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