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Web Security ApplianceApplication · Cisco

CVE-2016-1381

HIGH · 7.5 CVSS v3.0 Published 2016-05-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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 Cisco AsyncOS 8.5 through 9.0 before 9.0.1-162 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (memory consumption) via an HTTP file-range request for cached content, aka Bug ID CSCuw97270.

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

A memory leak vulnerability exists in Cisco AsyncOS versions 8.5 through 9.0 (before 9.0.1-162) on Web Security Appliance devices. Remote attackers can trigger the leak by sending HTTP file-range requests for cached content, causing memory consumption to grow until the device becomes unavailable.

MitigationApply Cisco firmware update 9.0.1-162 or later to resolve the memory leak. If immediate patching is not feasible, consider rate-limiting or blocking external HTTP range requests to the WSA as a temporary workaround.

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
Web Security ApplianceApplication
Affected:= 8.5.0-497= 8.5.0.000= 8.5.1-021= 8.5.2-024= 8.5.2-027= 8.5.3-055= 9.0.0-193= 9.0_base= 9.1.0-000= 9.1_base

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
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check the AsyncOS firmware version
    Log into the Cisco Web Security Appliance CLI and run the command to display the system version (for example, 'version' or 'show version'), or access the version information through the web GUI under System Administration > Software Updates.
    Affected if The version displayed is any of the following: 8.5.0-497, 8.5.0.000, 8.5.1-021, 8.5.2-024, 8.5.2-027, 8.5.3-055, 9.0.0-193, 9.0_base, 9.1.0-000, or 9.1_base.
  2. Verify the version is within the vulnerable range
    If your version starts with 8.5 or 9.0, confirm the full build number is before 9.0.1-162. Compare your exact version string against the affected ranges.
    Affected if The installed version is 8.5.x (any build) or 9.0.x/9.1.x but earlier than 9.0.1-162.
  3. Confirm web caching is enabled
    Check the WSA configuration through the web GUI under Security Services > Web Cache, or use the CLI command to show the caching configuration status.
    Affected if Web caching is turned on and the device is serving cached HTTP content to clients.
  4. Check if HTTP range requests are being processed
    Review the WSA proxy configuration to confirm that HTTP range request handling is active, or examine proxy logs for incoming requests containing Range headers.
    Affected if The device is configured to process HTTP requests with Range headers for cached objects.
  5. Monitor for excessive memory usage
    Check the system health or memory status via the WSA CLI (for example, 'status' or 'show memory') or through the web GUI monitoring dashboard.
    Affected if Memory usage is steadily increasing or shows abnormally high consumption that does not stabilize.

A user is affected if the WSA runs any AsyncOS version from 8.5.0 through 9.0 before build 9.0.1-162, has web caching enabled, and is processing HTTP range requests for cached content.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco firmware update 9.0.1-162 or later to resolve the memory leak. If immediate patching is not feasible, consider rate-limiting or blocking external HTTP range requests to the WSA as a temporary workaround.

Fix this in Web Security Appliance Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2016-1381 in production — separate from our analysis above.

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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
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  • Version or environment caveats, and links to real fixes
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