Description
In ISC DHCP 4.1-ESV-R1 -> 4.1-ESV-R16, ISC DHCP 4.4.0 -> 4.4.2 (Other branches of ISC DHCP (i.e., releases in the 4.0.x series or lower and releases in the 4.3.x series) are beyond their End-of-Life (EOL) and no longer supported by ISC. From inspection it is clear that the defect is also present in releases from those series, but they have not been officially tested for the vulnerability), The outcome of encountering the defect while reading a lease that will trigger it varies, according to: the component being affected (i.e., dhclient or dhcpd) whether the package was built as a 32-bit or 64-bit binary whether the compiler flag -fstack-protection-strong was used when compiling In dhclient, ISC has not successfully reproduced the error on a 64-bit system. However, on a 32-bit system it is possible to cause dhclient to crash when reading an improper lease, which could cause network connectivity problems for an affected system due to the absence of a running DHCP client process. In dhcpd, when run in DHCPv4 or DHCPv6 mode: if the dhcpd server binary was built for a 32-bit architecture AND the -fstack-protection-strong flag was specified to the compiler, dhcpd may exit while parsing a lease file containing an objectionable lease, resulting in lack of service to clients. Additionally, the offending lease and the lease immediately following it in the lease database may be improperly deleted. if the dhcpd server binary was built for a 64-bit architecture OR if the -fstack-protection-strong compiler flag was NOT specified, the crash will not occur, but it is possible for the offending lease and the lease which immediately followed it to be improperly deleted.
Published: 2021-05-26
Score: 7.4 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

No analysis available yet.

Remediation

Vendor Solution

Upgrade to the patched release most closely related to your current version of ISC DHCP: ISC DHCP 4.1-ESV-R16-P1 ISC DHCP 4.4.2-P1


Vendor Workaround

None known.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Debian DLA Debian DLA DLA-2674-1 isc-dhcp security update
EUVD EUVD EUVD-2021-12128 In ISC DHCP 4.1-ESV-R1 -> 4.1-ESV-R16, ISC DHCP 4.4.0 -> 4.4.2 (Other branches of ISC DHCP (i.e., releases in the 4.0.x series or lower and releases in the 4.3.x series) are beyond their End-of-Life (EOL) and no longer supported by ISC. From inspection it is clear that the defect is also present in releases from those series, but they have not been officially tested for the vulnerability), The outcome of encountering the defect while reading a lease that will trigger it varies, according to: the component being affected (i.e., dhclient or dhcpd) whether the package was built as a 32-bit or 64-bit binary whether the compiler flag -fstack-protection-strong was used when compiling In dhclient, ISC has not successfully reproduced the error on a 64-bit system. However, on a 32-bit system it is possible to cause dhclient to crash when reading an improper lease, which could cause network connectivity problems for an affected system due to the absence of a running DHCP client process. In dhcpd, when run in DHCPv4 or DHCPv6 mode: if the dhcpd server binary was built for a 32-bit architecture AND the -fstack-protection-strong flag was specified to the compiler, dhcpd may exit while parsing a lease file containing an objectionable lease, resulting in lack of service to clients. Additionally, the offending lease and the lease immediately following it in the lease database may be improperly deleted. if the dhcpd server binary was built for a 64-bit architecture OR if the -fstack-protection-strong compiler flag was NOT specified, the crash will not occur, but it is possible for the offending lease and the lease which immediately followed it to be improperly deleted.
Ubuntu USN Ubuntu USN USN-4969-1 DHCP vulnerability
Ubuntu USN Ubuntu USN USN-4969-2 DHCP vulnerability
History

Sat, 12 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00244}

epss

{'score': 0.00243}


Subscriptions

Debian Debian Linux
Fedoraproject Fedora
Isc Dhcp
Netapp Ontap Select Deploy Administration Utility Solidfire \& Hci Management Node
Redhat Enterprise Linux Openshift Rhel Aus Rhel E4s Rhel Els Rhel Eus Rhel Tus
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cve-icon MITRE

Status: PUBLISHED

Assigner: isc

Published:

Updated: 2024-09-16T22:08:32.175Z

Reserved: 2021-01-15T00:00:00.000Z

Link: CVE-2021-25217

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-05-26T22:15:07.947

Modified: 2024-11-21T05:54:34.013

Link: CVE-2021-25217

cve-icon Redhat

Severity : Important

Publid Date: 2021-05-26T00:00:00Z

Links: CVE-2021-25217 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses