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Adaptive Security Appliance SoftwareApplication · Cisco

CVE-2018-0101

CRITICAL · 10.0 CVSS v3.0 Published 2018-01-29
Fix available
A fix is available. Upgrade to 9.1.7.23 / 9.2.4.27 or later.
See remediation →
100/100
Remediation priority · Urgent
High EPSS Public exploit 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 Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause a reload of the affected system or to remotely execute code. The vulnerability is due to an attempt to double free a region of memory when the webvpn feature is enabled on the Cisco ASA device. An attacker could exploit this vulnerability by sending multiple, crafted XML packets to a webvpn-configured interface on the affected system. An exploit could allow the attacker to execute arbitrary code and obtain full control of the system, or cause a reload of the affected device. This vulnerability affects Cisco ASA Software that is running on the following Cisco products: 3000 Series Industrial Security Appliance (ISA), ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, ASA 1000V Cloud Firewall, Adaptive Security Virtual Appliance (ASAv), Firepower 2100 Series Security Appliance, Firepower 4110 Security Appliance, Firepower 9300 ASA Security Module, Firepower Threat Defense Software (FTD). Cisco Bug IDs: CSCvg35618.

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 double-free memory corruption vulnerability in the webvpn (SSL VPN) feature of Cisco ASA Software allows unauthenticated remote attackers to execute arbitrary code or cause device reload by sending crafted XML packets to affected interfaces. The vulnerability has a CVSS 10.0 rating due to the trivial exploitability and complete system compromise possible.

MitigationApply the Cisco patch for CSCvg35618; alternatively, disable webvpn if not required or restrict access to webvpn interfaces to reduce attack surface until patching is feasible.

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 SoftwareApplication
Affected:< 9.1.7.23>= 9.2.0, < 9.2.4.27>= 9.3.0, < 9.4.4.16>= 9.5.0, < 9.6.4.3>= 9.7.0, < 9.7.1.21>= 9.8.0, < 9.8.2.20>= 9.9.0, < 9.9.1.2
Secure Firewall Threat DefenseApplication
Affected:= 6.0.0= 6.0.1= 6.1.0= 6.2.0= 6.2.1= 6.2.2

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/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 ASA Software version
    Run the command 'show version' on the ASA CLI or check via ASDM. The output displays the software version in the format 'Version x.x.x'
    Affected if The installed version falls within any of these ranges: < 9.1.7.23; >= 9.2.0 and < 9.2.4.27; >= 9.3.0 and < 9.4.4.16; >= 9.5.0 and < 9.6.4.3; >= 9.7.0 and < 9.7.1.21; >= 9.8.0 and < 9.8.2.20; >= 9.9.0 and < 9.9.1.2
  2. Identify Cisco FTD version
    Run 'show version' on the FTD device or check via Firepower Management Center. The output displays the software version.
    Affected if The installed version is exactly 6.0.0, 6.0.1, 6.1.0, 6.2.0, 6.2.1, or 6.2.2
  3. Determine if webvpn is enabled on the ASA
    Run the command 'show run webvpn' or 'show vpn-sessiondb webvpn' in the ASA CLI. If any configuration appears (such as 'webvpn enable' under an interface or active sessions), webvpn is configured.
    Affected if webvpn is enabled or active on any interface (including internal). The vulnerability can be triggered by sending crafted XML packets to any webvpn-enabled interface.
  4. Check for active webvpn sessions
    Run 'show vpn-sessiondb webvpn' to display current webvpn sessions.
    Affected if Any active webvpn sessions indicate the feature is operational and exposed to the vulnerability if the version is affected.

The environment is affected if the installed Cisco ASA Software version or FTD version falls within the affected version ranges AND webvpn is enabled on the device.

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 9.1.7.23 / 9.2.4.27 / 9.4.4.16 or later
Fixed in 9.1.7.239.2.4.279.4.4.16
Interim mitigation

Apply the Cisco patch for CSCvg35618; alternatively, disable webvpn if not required or restrict access to webvpn interfaces to reduce attack surface until patching is feasible.

Recommended fix High confidence

ASA Software: 9.1.7.23, 9.2.4.27, 9.4.4.16, or 9.6.4.3 (or later stable releases) | FTD: 6.0.2+, 6.1.1+, 6.2.1+, or 6.3+

  1. 1. Identify the exact Cisco ASA Software version currently running using the 'show version' command
  2. 2. Identify if webvpn is enabled using 'show run webvpn' or 'show run | include webvpn'
  3. 3. For ASA Software: If running 9.1.x, upgrade to version 9.1.7.23 or later; for 9.2.x upgrade to 9.2.4.27 or later; for 9.3.x/9.4.x upgrade to 9.4.4.16 or later; for 9.5.x/9.6.x upgrade to 9.6.4.3 or later
  4. 4. For Secure Firewall Threat Defense (FTD): Upgrade from 6.0.0-6.0.1 to 6.0.2 or later; from 6.1.0 to 6.1.1 or later; from 6.2.0 to 6.2.1 or later, or migrate to version 6.3 or newer
  5. 5. Download the appropriate Cisco ASA software update from tools.cisco.com with valid service contract
  6. 6. Upload the new image to the ASA using 'copy tftp://<server>/<image> flash:'
  7. 7. Reload the new image using 'boot system <image>' followed by 'reload'
  8. 8. After upgrade, verify webvpn configuration and test SSL VPN functionality
Caveat Major ASA upgrades may require configuration changes; always review Cisco release notes for migration considerations and test in lab environment before production deployment

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

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,180
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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-2018-0101 in production — separate from our analysis above.

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