CVE-2026-29004Public exploit

Code execution via undersized DNS option allocation

Published May 4, 2026 · Updated May 4, 2026

Heap overflow in BusyBox before commit 42202bf allows network-adjacent attackers to corrupt memory via a crafted DHCPv6 response. In option_to_env(), a zero-length DNS_SERVERS payload produces a three-byte allocation before stpcpy writes the five-byte "dns=" string and terminator. Exploitation requires an active udhcpc6 client accepting the attacker's reply and results in a crash or code execution where heap hardening is absent.

CVSS severity7.2
High
EPSS probability0.38%
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 BusyBox before commit 42202bf allows network-adjacent attackers to corrupt memory via a crafted DHCPv6 response. In option_to_env(), a zero-length DNS_SERVERS payload produces a three-byte allocation before stpcpy writes the five-byte "dns=" string and terminator. Exploitation requires an active udhcpc6 client accepting the attacker's reply and results in a crash or code execution where heap hardening is absent.

The record

CVE
CVE-2026-29004
Published
May 4, 2026
Updated
May 4, 2026
Vendor
BusyBox
Product
BusyBox
Classifications
CWE-122, CWE-131, T1203
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 4, 2026CVE publishedPublication date reported by the CVE source.
  2. May 4, 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 <42202bfb1e6ac51fa995beda8be4d7b654aeee2a

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

BusyBox · BusyBoxversion=0 <42202bfb1e6ac51fa995beda8be4d7b654aeee2a

Published CVSS scores

8.1VulnCheckCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
8.8Red HatCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.2VulnCheckCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
CWE-131Incorrect Calculation of Buffer Size
T1203Exploitation for Client Execution

Public exploit references

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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