CVE-2026-56115

Same-link service interruption via prefix-exclude overflow

Published Jun 23, 2026 · Updated Jun 23, 2026

Out-of-bounds write in dhcp6_makemessage in dhcpcd 10.3.2 and earlier allows remote attackers on the same link to interrupt the client. The function serializes a 17-byte RFC 6603 OPTION_PD_EXCLUDE body into a fixed 16-byte local buffer, causing a one-byte overwrite. No credentials or user interaction are required when a crafted DHCPv6 ADVERTISE carries an IA_PD IAPREFIX /0 and an exclude length of /121 through /128.

CVSS severity6.0
Medium
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in dhcp6_makemessage in dhcpcd 10.3.2 and earlier allows remote attackers on the same link to interrupt the client. The function serializes a 17-byte RFC 6603 OPTION_PD_EXCLUDE body into a fixed 16-byte local buffer, causing a one-byte overwrite. No credentials or user interaction are required when a crafted DHCPv6 ADVERTISE carries an IA_PD IAPREFIX /0 and an exclude length of /121 through /128.

The record

CVE
CVE-2026-56115
Published
Jun 23, 2026
Updated
Jun 23, 2026
Vendor
Network Configuration
Product
dhcpcd
Classifications
CWE-787, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 23, 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=0 <=10.3.2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Network Configuration · dhcpcdversion=0 <=10.3.2

Published CVSS scores

6.0VulnCheckCVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.3VulnCheckCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
6.5NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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