CVE-2026-42512Network attack vector

Remote heap overwrite via undersized environment-array reallocation

Published Apr 30, 2026 · Updated Apr 30, 2026

Heap-based buffer overflow in FreeBSD dhclient allows remote attackers to overwrite heap memory via a crafted DHCP packet. The environment builder miscalculates the allocation size when growing its string-pointer array for dhclient-script, so appended entries write beyond the heap buffer. Reachability requires dhclient to process the packet; a crash is confirmed, while successful code execution has not been publicly demonstrated.

CVSS severity8.1
High
EPSS probability1.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in FreeBSD dhclient allows remote attackers to overwrite heap memory via a crafted DHCP packet. The environment builder miscalculates the allocation size when growing its string-pointer array for dhclient-script, so appended entries write beyond the heap buffer. Reachability requires dhclient to process the packet; a crash is confirmed, while successful code execution has not been publicly demonstrated.

The record

CVE
CVE-2026-42512
Published
Apr 30, 2026
Updated
Apr 30, 2026
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-122, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=13.5-RELEASE <p13
  2. Affected versionversion=14.3-RELEASE <p12
  3. Affected versionversion=14.4-RELEASE <p3
  4. Affected versionversion=15.0-RELEASE <p7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=13.5-RELEASE <p13; version=14.3-RELEASE <p12; version=14.4-RELEASE <p3; version=15.0-RELEASE <p7

Published CVSS scores

8.1CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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