Linux Kernel BPF Redirect Helpers skb_do_redirect null pointer dereference

Summaryinfo

A vulnerability has been found in Linux Kernel and classified as problematic. This vulnerability affects the function skb_do_redirect of the component BPF Redirect Helpers. Performing a manipulation results in null pointer dereference. This vulnerability is identified as CVE-2026-68337. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in Linux Kernel (the affected version unknown). This affects the function skb_do_redirect of the component BPF Redirect Helpers. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject redirect helpers without a bpf_net_context The bpf_redirect*() helpers and skb_do_redirect() obtain the per-task bpf_redirect_info via bpf_net_ctx_get_ri(), which dereferences the current->bpf_net_context unconditionally. That context is established on the paths that run tc BPF such as sch_handle_{ingress,egress}(), *except* for the case where {cls,act}_bpf was attached to a proper qdisc. A program running from there reaches the NULL deref in two ways: * It calls bpf_redirect() directly, which dereferences the context at the top of the helper: tc qdisc add dev eth0 root handle 1: red limit 1MB min 10KB max 20KB \ avpkt 1000 burst 100 qevent early_drop block 10 tc filter add block 10 pref 1 bpf obj redirect.o * It simply returns TC_ACT_REDIRECT without helper call: tcf_qevent_handle() then dispatches to skb_do_redirect(), which dereferences the context Rather than extending bpf_net_context management into the qdisc path, make the redirect helpers refuse to operate when no context exists, and have tcf_qevent_handle() drop a TC_ACT_REDIRECT verdict instead of calling skb_do_redirect(). Previous behaviour was a crash, so nothing regresses by not supporting it.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-68337 since 07/30/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. The exploitation needs additional levels of successful authentication. Technical details are known, but no exploit is available.

Applying the patch cabfacbd5af09d3ae898ca224c4a1459e9bba15d/3f4920d165b29052255527d8ae7619e7ec132ece is able to eliminate this problem.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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