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Web Security ApplianceApplication · Cisco

CVE-2022-20784

MEDIUM · 5.3 CVSS v3.1 Published 2022-04-06
Fix available
A fix is available. Upgrade to 14.0.2 or later.
See remediation →
62/100
Remediation priority · Elevated
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
A vulnerability in the Web-Based Reputation Score (WBRS) engine of Cisco AsyncOS Software for Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to bypass established web request policies and access blocked content on an affected device. This vulnerability is due to incorrect handling of certain character combinations inserted into a URL. An attacker could exploit this vulnerability by sending crafted URLs to be processed by an affected device. A successful exploit could allow the attacker to bypass the web proxy and access web content that has been blocked by policy.

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

A vulnerability in the Web-Based Reputation Score (WBRS) engine of Cisco AsyncOS Software for Cisco Web Security Appliance allows unauthenticated remote attackers to bypass web request policies by sending URLs containing certain crafted character combinations. The WBRS engine incorrectly processes these character sequences, causing the web proxy to fail to apply blocked content policies.

MitigationApply the vendor-provided patch or upgrade to a fixed version of Cisco AsyncOS Software for WSA. Additionally, review and verify web proxy policies are functioning correctly after the update.

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:>= 11.7.0, < 14.0.2

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
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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 Cisco WSA AsyncOS version
    Log into the WSA CLI and run the command 'version' or access the web interface under System Administration > Software Upgrade to view the installed AsyncOS version
    Affected if The installed version is greater than or equal to 11.7.0 and less than 14.0.2
  2. Verify WBRS engine is enabled
    In the WSA web interface, navigate to Security Services > Web-Based Reputation Score (WBRS) and confirm the service status shows as 'Enabled'
    Affected if WBRS is enabled and the AsyncOS version falls within the affected range
  3. Confirm web proxy is active
    In the WSA web interface, check under Network > Web Proxy or run 'proxyconfig' in CLI to verify the web proxy service is running and configured
    Affected if Web proxy is enabled and the WBRS engine is active with a vulnerable AsyncOS version
  4. Review web access policy logs for policy bypass
    In the WSA web interface, navigate to Reporting > Web Activity Logs or use the 'grep' command in CLI to search for URLs containing unusual character sequences (such as combinations of encoded characters or special characters) that may have bypassed content filters
    Affected if Logs show URLs with crafted character sequences that were allowed despite matching block policies, indicating potential exploitation of this vulnerability

A user is affected if their Cisco Web Security Appliance runs AsyncOS version 11.7.0 through 14.0.1 (exclusive of 14.0.2) with WBRS enabled and the web proxy is active.

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.

dbcve · scoped
Upgrade available Upgrade to 14.0.2 or later
Fixed in 14.0.2
Interim mitigation

Apply the vendor-provided patch or upgrade to a fixed version of Cisco AsyncOS Software for WSA. Additionally, review and verify web proxy policies are functioning correctly after the update.

Recommended fix High confidence

14.0.2

  1. Log into the Cisco WSA CLI or web UI and note the current AsyncOS version (e.g., run 'version' or check System Administration > System Status).
  2. Schedule a maintenance window to minimize disruption.
  3. Obtain the fixed AsyncOS image (version 14.0.2 or later) from Cisco (requires a valid service contract).
  4. Back up the current WSA configuration (use the 'backup' command in CLI or UI).
  5. Upload the new AsyncOS image via the web UI (System Administration > System Upgrade) or CLI (e.g., 'upgrade' command).
  6. Initiate the upgrade and allow the appliance to reboot; this may take several minutes.
  7. After reboot, verify the new version is installed (run 'version' or check the web UI) and confirm the WBRS bypass vulnerability is resolved.
Caveat Review the 14.0.x release notes for any configuration or feature changes before upgrading.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Web Security Appliance Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2022-20784 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
  • 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