CVE-2020-7461Network attack vector

Sandboxed code execution via undersized option buffer

Published Mar 26, 2021 · Updated Aug 4, 2024

Heap overflow in FreeBSD dhclient allows remote attackers on the local network to execute code via malformed DHCP option 119 data. When expanding a compressed domain-search list, the option parser undercounts the required length, allocates an undersized heap buffer, and copies the uncompressed list into it. A malicious DHCP server must answer the client on its network segment; resulting code runs with reduced privileges inside the dhclient Capsicum sandbox.

CVSS severity7.3
High
EPSS probability4.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap overflow in FreeBSD dhclient allows remote attackers on the local network to execute code via malformed DHCP option 119 data. When expanding a compressed domain-search list, the option parser undercounts the required length, allocates an undersized heap buffer, and copies the uncompressed list into it. A malicious DHCP server must answer the client on its network segment; resulting code runs with reduced privileges inside the dhclient Capsicum sandbox.

The record

CVE
CVE-2020-7461
Published
Mar 26, 2021
Updated
Aug 4, 2024
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-787, T1557.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=FreeBSD 12.1-RELEASE before p9, 11.4-RELEASE before p3, 11.3-RELEASE before p13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=FreeBSD 12.1-RELEASE before p9, 11.4-RELEASE before p3, 11.3-RELEASE before p13

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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-787Out-of-bounds Write
T1557.003Adversary-in-the-Middle: DHCP Spoofing

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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