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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Hardened Images | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | busybox | No fix yet | — |
| Ubuntu 26.04 LTS | busybox | No fix yet | — |
| Ubuntu 24.04 LTS | busybox | No fix yet | — |
| Ubuntu 22.04 LTS | busybox | No fix yet | — |
| Ubuntu 20.04 LTS | busybox | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | busybox | No fix yet | — |
| Ubuntu Pro 16.04 LTS | busybox | No fix yet | — |
| Ubuntu Pro 14.04 LTS | busybox | No fix yet | — |
Advisories 1
- WID-SEC-2026-4451 BusyBox: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
References
- https://access.redhat.com/security/cve/CVE-2026-124740 vdb-entry
- RHBZ#2571616 issue-tracking