VulnerabilityPublished 11 Nov 2026

CVE-2026-124740: BusyBox's udhcpc6 DHCPv6 client · Use After Free

Source GCVE Database

Compare

Authoritative record:CVE-2026-124740· Medium 4.3

Not known to be exploited · CVSS 4.3 Medium.

Data as of 11 Nov 2026, 13:33 UTC

CVSS 3.1 base score

4.3Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (redhat)	CVSS 3.1	4.3

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-9f82-ccff-m2qq

What to do

Affected software

Product	Affected	Fixed in
Red Hat Enterprise Linux 6busybox	Affected–	Fixed in–
Red Hat Hardened Imagesbusybox	Affected–	Fixed in–

AI-suggested

Currently, no mitigation meeting Red Hat's criteria for ease of use, applicability, or stability is available. Users should avoid running BusyBox udhcpc6 DHCPv6 client in environments where exposure to rogue DHCPv6 servers on the local network is possible. Standard Red Hat Enterprise Linux users relying on NetworkManager are not affected. Monitor Red Hat advisories for any future updates or fixes.

Description

A use-after-free vulnerability exists in BusyBox's udhcpc6 DHCPv6 client. A malicious local network DHCPv6 server can send a crafted reply packet without usable address options, triggering the flaw. This causes the client to read stale heap memory, potentially leading to a denial of service via application crash or disclosure of previously assigned network address data. The vulnerability requires an attacker on the local network and affects environments where BusyBox udhcpc6 is explicitly used, such as custom setups or containers. Standard Red Hat Enterprise Linux installations are not affected as they use NetworkManager by default.

Impact

The vulnerability allows an adjacent attacker operating a rogue DHCPv6 server to cause the BusyBox udhcpc6 client to crash (denial of service) or disclose stale heap memory containing previously assigned network address information. There is no impact on confidentiality or integrity beyond this data disclosure and availability impact. The flaw does not affect default Red Hat Enterprise Linux installations using NetworkManager, restricting risk to specific custom or containerized environments.

CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 13:33 UTC

WeaknessesCWE-416

Technical details

References

Community reviews

Related threats