iOSOperating system · Cisco
CVE-2018-0154
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 crypto engine of the Cisco Integrated Services Module for VPN (ISM-VPN) running Cisco IOS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient handling of VPN traffic by the affected device. An attacker could exploit this vulnerability by sending crafted VPN traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to hang or crash, resulting in a DoS condition. Cisco Bug IDs: CSCvd39267.
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 vulnerability exists in the crypto engine of Cisco Integrated Services Module for VPN (ISM-VPN) devices running Cisco IOS Software. The vulnerability stems from insufficient handling of VPN traffic, allowing an unauthenticated remote attacker to send specially crafted VPN packets to an affected device. Successful exploitation causes the device to hang or crash, resulting in a denial of service condition.
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
iOSOperating system
all versionsCVSS 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:3.1/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 checksWork through these to decide whether this CVE applies to you.
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Identify if the device is an ISM-VPN moduleUse 'show module' or 'show hardware' command to confirm the device is a Cisco Integrated Services Module for VPN (ISM-VPN)Affected if The device is an ISM-VPN module running any Cisco iOS version
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Confirm the Cisco iOS versionUse 'show version' to display the running iOS versionAffected if Any version of Cisco iOS is running on the ISM-VPN module (the vulnerability affects all versions)
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Verify VPN functionality is enabledUse 'show crypto ipsec sa' or 'show vpn-sessiondb' to check if any IPSec VPN tunnels or crypto configurations are activeAffected if VPN/crypto features are configured and active on the device
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Check for crash or hang indicatorsReview 'show crashinfo' or 'show log' for recent system crashes, hangs, or unexpected restartsAffected if Device has experienced unexplained crashes or hangs that coincide with VPN traffic processing
You are affected if this is an ISM-VPN module running Cisco iOS with active VPN/crypto configuration, as the vulnerability requires the crypto engine to be engaged by incoming VPN traffic.
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 dataApply the appropriate Cisco IOS software update for the ISM-VPN module when available from Cisco. In the interim, consider implementing ingress filtering or rate limiting on VPN traffic at network boundaries to reduce exposure to crafted packets.
Fix this in iOS
Exploited in the wild — priority engagement
- Consultation4.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,968.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-0154 — 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-2018-0154 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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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.
- 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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