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Adaptive Security Appliance 5500Hardware / appliance · Cisco

CVE-2009-4455

MEDIUM · 6.5 CVSS v2.0 Published 2009-12-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable 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
The default configuration of Cisco ASA 5500 Series Adaptive Security Appliance (Cisco ASA) 7.0, 7.1, 7.2, 8.0, 8.1, and 8.2 allows portal traffic to access arbitrary backend servers, which might allow remote authenticated users to bypass intended access restrictions and access unauthorized web sites via a crafted URL obfuscated with ROT13 and a certain encoding. NOTE: this issue was originally reported as a vulnerability related to lack of restrictions to URLs listed in the Cisco WebVPN bookmark component, but the vendor states that "The bookmark feature is not a security feature."

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

Cisco ASA 5500 Series WebVPN portal in versions 7.0-8.2 has a default configuration that allows authenticated remote users to access arbitrary backend servers via the VPN. Attackers use crafted URLs obfuscated with ROT13 and encoding to bypass intended access restrictions and reach unauthorized internal resources.

MitigationConfigure strict access control policies on the ASA WebVPN to restrict portal traffic to explicitly authorized backend servers, and implement URL filtering to block obfuscated or suspicious request patterns.

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
Adaptive Security Appliance 5500Hardware / appliance
Affected:= 7.0= 7.1= 7.2= 8.0= 8.1= 8.2

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
Authentication
Single
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:L/Au:S/C:P/I:P/A:P

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 the Cisco ASA version
    Run 'show version' on the ASA CLI or check via ASDM to determine the installed software version
    Affected if The version is 7.0, 7.1, 7.2, 8.0, 8.1, or 8.2
  2. Confirm WebVPN portal is enabled
    Run 'show webvpn' or check the configuration with 'show run webvpn' to see if the WebVPN feature is active
    Affected if WebVPN is enabled and configured on the device
  3. Check the default WebVPN server access configuration
    Examine the WebVPN group policy or tunnel group settings for 'webvpn' configuration, specifically looking at any 'url-list' or server access definitions
    Affected if No explicit allowlist of backend servers is configured, allowing access to arbitrary internal resources by default
  4. Inspect portal access control policies
    Review the ASA access-list configurations applied to the WebVPN session, checking for restrictive filters on the portal's URL access
    Affected if There are no strict access control policies restricting portal users to specific backend servers
  5. Look for URL filtering or request monitoring
    Check if any additional URL filtering, intrusion prevention, or request logging is configured to detect obfuscated patterns like ROT13 or encoded requests
    Affected if No URL filtering or monitoring exists to block or detect obfuscated request patterns

The environment is affected if the ASA runs version 7.0-8.2 with WebVPN enabled and lacks strict access control policies restricting portal users to explicitly authorized backend servers.

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

Configure strict access control policies on the ASA WebVPN to restrict portal traffic to explicitly authorized backend servers, and implement URL filtering to block obfuscated or suspicious request patterns.

Fix this in Adaptive Security Appliance 5500 Scoped from the published advisory
  • Consultation6.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,780
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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-2009-4455 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
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  • Version or environment caveats, and links to real fixes
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