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CVE-2021-25217 ISC DHCP

Affected softwareISC DHCP
Severity7.4 High CVSS 3.1 3 scores
WeaknessBuffer errors (CWE-119)
Published26 May 2021
Updated17 Jun 2026

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.

Exploitation status

No public exploit

No exploit has been reported in the sources we check. Published 5 years ago.
  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment no assessment published
  • Indexed PoC none indexed
  • EPSS 6.1% chance in 30 days

Waratek protection

Outside Waratek scope

A Java vulnerability, but not one Waratek protects. It affects only Java on a user's desktop (applets, Web Start, JavaFX, the installer), sits in a product the Waratek agent can't be installed into, or is in a package we don't expect in business applications. The decision below says which.

  • Protection none
  • Action not pursued none
  • Review human Researcher
  • Record active
Decided by Manual classification of this CVE in the legacy dataset
Finding A manual classification set this CVE's status to Outside Waratek scope, but the CVE names a tracked product.

CVSS

7.4 HIGH v3.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H 3 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

VersionScoreBandVectorAssignerType
CVSS 3.1 7.4 HIGH CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H security-officer@isc.org Secondary published
CVSS 3.1 7.4 HIGH CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H NVD Secondary
CVSS 2.0 3.3 none AV:A/AC:L/Au:N/C:N/I:N/A:P NVD Primary

Affected software and releases

Products and versions

16 products, 47 version entries
SourceVendorProductSchemeAffected versions
nvd debian debian linux generic 9.0
nvd fedoraproject fedora generic 33 · 34
nvd isc dhcp generic 4.1-esv:r1 · 4.1-esv:r10 · 4.1-esv:r10_rc1 · 4.1-esv:r10rc1 · 4.1-esv:r10_b1 · 4.1-esv:r10b1 · 4.1-esv:r11 · 4.1-esv:r11_rc1 · 4.1-esv:r11_rc2 · 4.1-esv:r11rc1 · 4.1-esv:r11rc2 · 4.1-esv:r11_b1 · 4.1-esv:r11b1 · 4.1-esv:r12 · 4.1-esv:r12-p1 · 4.1-esv:r12_b1 · 4.1-esv:r12_p1 · 4.1-esv:r12b1 · 4.1-esv:r13 · 4.1-esv:r13_b1 · 4.1-esv:r13b1 · 4.1-esv:r14 · 4.1-esv:r14_b1 · 4.1-esv:r14b1 · 4.1-esv:r15 · 4.1-esv:r15-p1 · 4.1-esv:r15_b1 · 4.1-esv:r16 · ≥ 4.4.0 and ≤ 4.4.2
nvd netapp ontap select deploy administration utility generic any version
nvd netapp solidfire \& hci management node generic any version
nvd siemens ruggedcom rox mx5000 firmware generic ≥ 2.3.0 and ＜ 2.15.0
nvd siemens ruggedcom rox rx1400 firmware generic ＜ 2.15.0
nvd siemens ruggedcom rox rx1500 firmware generic ≥ 2.3.0 and ＜ 2.15.0
nvd siemens ruggedcom rox rx1501 firmware generic ≥ 2.3.0 and ＜ 2.15.0
nvd siemens ruggedcom rox rx1510 firmware generic ≥ 2.3.0 and ＜ 2.15.0
nvd siemens ruggedcom rox rx1511 firmware generic ≥ 2.3.0 and ＜ 2.15.0
nvd siemens ruggedcom rox rx1512 firmware generic ≥ 2.3.0 and ＜ 2.15.0
nvd siemens ruggedcom rox rx1524 firmware generic ＜ 2.15.0
nvd siemens ruggedcom rox rx1536 firmware generic ＜ 2.15.0
nvd siemens ruggedcom rox rx5000 firmware generic ≥ 2.3.0 and ＜ 2.15.0
nvd siemens sinec ins generic 1.0 · ＜ 1.0 · 1.0:sp1

References

URLTags
http://www.openwall.com/lists/oss-security/2021/05/26/6 Mailing List, Patch, Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-406691.pdf Patch, Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-637483.pdf Patch, Third Party Advisory
https://kb.isc.org/docs/cve-2021-25217 Exploit, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00002.html Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5QI4DYC7J4BGHEW3NH4XHMWTHYC36UK4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z2LB42JWIV4M4WDNXX5VGIP26FEYWKIF/
https://security.gentoo.org/glsa/202305-22
https://security.netapp.com/advisory/ntap-20220325-0011/ Third Party Advisory

Timeline
Published2021-05-26By the CVE Program.
NVD record modified2026-06-17NVD's own last-modified date for this record.