What’s Vulnerable › Vulnerabilities

CVE-2018-5732: A specially constructed response from a malicious server can cause a buffer overflow in dhclient

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-10-09 · updated 2026-06-17
• Weakness: CWE-119

Description

Failure to properly bounds-check a buffer used for processing DHCP options allows a malicious server (or an entity masquerading as a server) to cause a buffer overflow (and resulting crash) in dhclient by sending a response containing a specially constructed options section. Affects ISC DHCP versions 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0

Affected products

• ISC DHCP: from 4.1.0 through 4.1.2; from 4.2.0 before 4.2.8; from 4.3.0 before 4.3.6; 4.1-esv, 4.1-esv-r1, 4.1-esv-r10, 4.1-esv-r10b1, 4.1-esv-r10rc1, 4.1-esv-r11 (+29) — fixed in 4.2.8, 4.3.6

How to fix

Upgrade to a fixed version: ISC DHCP 4.2.8, 4.3.6. Check the vendor advisory for mitigations.

References

• https://kb.isc.org/docs/aa-01565
• https://kb.isc.org/docs/aa-01565

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