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Web Security Appliance \(wsa\)Application · Cisco

CVE-2016-1383

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 through 8.8 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (memory consumption) via an unspecified HTTP status code, aka Bug ID CSCur28305.

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 · moderate confidence

Memory leak vulnerability in Cisco AsyncOS (versions through 8.8) on Web Security Appliance devices. The vulnerability is triggered by specific HTTP status codes, causing memory consumption to grow unbounded, eventually leading to denial of service when system resources are exhausted.

MitigationApply the Cisco security update for AsyncOS to a version beyond 8.8 once available. As an interim measure, consider rate limiting or filtering the specific HTTP status codes triggering the leak if identifiable, and monitor memory usage on WSA devices closely.

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 Appliance \(wsa\)Application
Affected:= 5.6.0-623= 6.0.0-000= 7.1.0= 7.1.1= 7.1.2= 7.1.3= 7.1.4= 7.5.0-000= 7.5.0-825= 7.5.1-000= 7.5.2-000= 7.7.0-000

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. Identify Cisco WSA deployment
    Check network inventory or scan for Cisco Web Security Appliance devices in the environment. Look for devices responding with Cisco WSA web interface or SNMP community strings indicating 'wsa' or 'Web Security Appliance'.
    Affected if A Cisco WSA device is found in the environment.
  2. Check AsyncOS version
    Log into the WSA CLI and run the 'version' command, or check via the web GUI under System Administration > Software Version. Compare the displayed AsyncOS version against the affected list: 5.6.0-623, 6.0.0-000, 7.1.0 through 7.1.4, 7.5.0-000 through 7.5.2-000, 7.7.0-000, or any version through 8.8.
    Affected if The installed AsyncOS version matches one of the affected versions listed or is any version through 8.8.
  3. Verify web proxy or HTTP scanning is enabled
    Log into the WSA and check if the Web Proxy service is enabled. In the GUI, navigate to Security Services > Web Proxy, or run 'proxy' command in CLI. Confirm the proxy is actively accepting and processing HTTP traffic.
    Affected if Web Proxy or HTTP content scanning is enabled and processing user requests.
  4. Monitor memory consumption on WSA
    Run 'status' or 'memory' command in the WSA CLI, or check via SNMP using OIDs for device memory. Look for steadily increasing memory usage over time, particularly when the device handles HTTP traffic returning specific status codes.
    Affected if Memory usage grows unbounded without returning to baseline levels, especially under sustained HTTP traffic.

The environment is affected if a Cisco WSA is deployed with AsyncOS version 8.8 or earlier and the web proxy is enabled, with memory usage exhibiting unbounded growth during HTTP traffic processing.

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 the Cisco security update for AsyncOS to a version beyond 8.8 once available. As an interim measure, consider rate limiting or filtering the specific HTTP status codes triggering the leak if identifiable, and monitor memory usage on WSA devices closely.

Fix this in Web Security Appliance \(wsa\) Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing6.0 h
  • Review / QA3.0 h
19.0 hours of engineering $3,320
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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-2016-1383 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