CVE-2018-5733: A malicious client can overflow a reference counter in ISC dhcpd
  • 16 Nov 2018
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CVE-2018-5733: A malicious client can overflow a reference counter in ISC dhcpd

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Article Summary

CVE: CVE-2018-5733

Document version: 2.0

Posting date: 28 February 2018

Program impacted: ISC DHCP

Versions affected: 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0

Severity: Medium

Exploitable: Remotely

Description:

A malicious client which is allowed to send very large amounts of traffic (billions of packets) to a DHCP server can eventually overflow a 32-bit reference counter, potentially causing dhcpd to crash.

Impact:

Successful exploitation of this vulnerability may exhaust the memory available to dhcpd and/or cause it to crash, resulting in a denial of service to clients.

CVSS Score: 5.9

CVSS Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Workarounds: None.

Active exploits: No known active exploits.

Solution: Upgrade to the patched release most closely related to your current version of DHCP. These are all available at https://www.isc.org/downloads.

  • DHCP 4.1-ESV-R15-P1
  • DHCP 4.3.6-P1
  • DHCP 4.4.1

Acknowledgements: ISC would like to thank Felix Wilhelm, Google Security Team, for reporting this vulnerability.

Document Revision History:

1.0 Advance Notification, 21 February 2018
2.0 Public Disclosure, 28 February 2018

Related documents:

Do you still have questions? Questions regarding this advisory should go to security-officer@isc.org. To report a new issue, please encrypt your message using security-officer@isc.org's PGP key which can be found here: https://www.isc.org/downloads/software-support-policy/openpgp-key/. If you are unable to use encrypted email, you may also report new issues at: https://www.isc.org/community/report-bug/.

Note:

ISC patches only currently supported versions. When possible we indicate EOL versions affected. (For current information on which versions are actively supported, please see https://www.isc.org/downloads/.)

ISC Security Vulnerability Disclosure Policy:

Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy.

This Knowledgebase article is the complete and official security advisory document.

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