CVE-2026-124740
Busybox: use-after-free of requested_ipv6 in udhcpc6
CVE-2026-124740 is a medium vulnerability (CVSS 4.3) in Red Hat Enterprise Linux 6, published November 11, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.20%, the 10th percentile. No source names a fixed version.
- Severity
- 4.3 MediumCVSS 3.1, CVE List
- Exploit chance
- 0.20%EPSS, 10th percentile
- Exploitation
- None knownNot on CISA’s or ENISA’s lists
- Fixed in
- No fix listedNo source names one
Description
A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
Discussion
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
busyboxUbuntu:Pro:14.04:LTS | All versions, plus listed versions 1:1.20.0-8.1ubuntu11:1.20.0-9ubuntu11:1.20.0-9ubuntu21:1.21.0-1ubuntu11:1.21.0-1ubuntu1.41:1.21.0-1ubuntu1.4+esm1 | None known |
busyboxUbuntu:Pro:16.04:LTS | All versions, plus listed versions 1:1.22.0-15ubuntu11:1.22.0-15ubuntu1.41:1.22.0-15ubuntu1.4+esm11:1.22.0-15ubuntu1.4+esm2 | None known |
busyboxUbuntu:Pro:18.04:LTS | All versions, plus listed versions 1:1.22.0-19ubuntu21:1.27.2-1ubuntu31:1.27.2-1ubuntu41:1.27.2-2ubuntu21:1.27.2-2ubuntu3 Show 5 moreShow less1:1.27.2-2ubuntu3.11:1.27.2-2ubuntu3.21:1.27.2-2ubuntu3.31:1.27.2-2ubuntu3.41:1.27.2-2ubuntu3.4+esm1 | None known |
busyboxUbuntu:20.04:LTS | All versions, plus listed versions 1:1.30.1-4ubuntu41:1.30.1-4ubuntu51:1.30.1-4ubuntu61:1.30.1-4ubuntu6.11:1.30.1-4ubuntu6.21:1.30.1-4ubuntu6.31:1.30.1-4ubuntu6.41:1.30.1-4ubuntu6.5 | None known |
busyboxUbuntu:22.04:LTS | All versions, plus listed versions 1:1.30.1-6ubuntu31:1.30.1-7ubuntu11:1.30.1-7ubuntu21:1.30.1-7ubuntu31:1.30.1-7ubuntu3.1 | None known |
busyboxUbuntu:24.04:LTS | All versions, plus listed versions 1:1.36.1-3ubuntu11:1.36.1-6ubuntu11:1.36.1-6ubuntu31:1.36.1-6ubuntu3.1 | None known |
busyboxUbuntu:26.10 | All versions, plus listed versions 1:1.37.0-7ubuntu11:1.37.0-10.1ubuntu21:1.37.0-10.1ubuntu31:1.38.0-3ubuntu11:1.38.0-3ubuntu31:1.38.0-3ubuntu4 | None known |
busyboxUbuntu:26.04:LTS | All versions, plus listed versions 1:1.37.0-4ubuntu11:1.37.0-7ubuntu1 | None known |
What each source reports
CVE List Score used
Busybox: use-after-free of requested_ipv6 in udhcpc6
A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests.
- Record
CVE-2026-124740- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-416
- Updated
- 2026-11-11
EUVDEUVD-2026-123358
A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests.
- Record
EUVD-2026-123358- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Updated
- 2026-11-11
GitHub AdvisoriesGHSA-9f82-ccff-m2qq
A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can...
A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests.
- Record
GHSA-9f82-ccff-m2qq- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-416
- Updated
- 2026-11-11
NVD
A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests.
- Record
CVE-2026-124740- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-416
- Updated
- 2026-11-12
OSVUBUNTU-CVE-2026-124740
A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests.
- Record
UBUNTU-CVE-2026-124740- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Updated
- 2026-11-13
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | NVD, OSV | |
| published | EUVD, NVD | |
| published | EUVD | |
| products, references, severity, title | CVE List | |
| aliases, cwes, references, severity, title | GitHub Advisories | |
| first indexed | EUVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.