Adaptive Security Appliance SoftwareApplication · Cisco
CVE-2018-15388
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 · uneditedA vulnerability in the WebVPN login process of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause increased CPU utilization on an affected device. The vulnerability is due to excessive processing load for existing WebVPN login operations. An attacker could exploit this vulnerability by sending multiple WebVPN login requests to the device. A successful exploit could allow the attacker to increase CPU load on the device, resulting in a denial of service (DoS) condition.
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 confidenceA denial of service vulnerability in Cisco ASA and FTD WebVPN login processing allows an unauthenticated remote attacker to send multiple login requests, causing excessive CPU load on the affected device due to inefficient processing of these requests.
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
< 9.4.4.34>= 9.5, < 9.6.4.25>= 9.7, < 9.8.4>= 9.9, < 9.9.2.50
Secure Firewall Threat DefenseApplication
< 6.2.3.12CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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 checksWork through these to decide whether this CVE applies to you.
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Verify if WebVPN is enabled on the deviceRun the command 'show webvpn' in ASA/FTD CLI or check the configuration with 'show running-config webvpn'Affected if WebVPN is enabled and configured - the vulnerability only affects devices with WebVPN feature active
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Check the installed ASA software versionRun the command 'show version' in ASA CLI and look for the software version number in the outputAffected if Version matches any of these ranges: < 9.4.4.34 OR >= 9.5 AND < 9.6.4.25 OR >= 9.7 AND < 9.8.4 OR >= 9.9 AND < 9.9.2.50
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Check the installed FTD software versionRun 'show version' in FTD CLI or access the FTD management console to view the software versionAffected if Version is lower than 6.2.3.12
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Check for high CPU usage from WebVPN processesRun 'show processes cpu history' and look for elevated CPU usage; use 'show processes' to identify WebVPN-related processes consuming excessive CPUAffected if WebVPN or sslvpnd processes are consuming unusually high CPU, especially during login attempts
A user is affected if WebVPN is enabled and the installed ASA or FTD version falls within any of the vulnerable version ranges listed.
Generated from the published advisory. Verify against your own configuration.
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 data6.2.3.129.4.4.349.6.4.25
Apply the Cisco software update for CVE-2018-15388 when available, or implement rate limiting on WebVPN login endpoints and restrict WebVPN access to authorized IP ranges as a temporary workaround.
Fix this in Adaptive Security Appliance Software
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-15388 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2018-15388 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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