Linux Kernel up to 7.1.8 BPF __bpf_nf_ct_lookup/__bpf_nf_ct_alloc_entry opts null pointer dereference

Summaryinfo

A vulnerability identified as problematic has been detected in Linux Kernel up to 7.1.8. This affects the function __bpf_nf_ct_lookup/__bpf_nf_ct_alloc_entry of the component BPF. This manipulation of the argument opts causes null pointer dereference. This vulnerability is handled as CVE-2026-74715. It is possible to launch the attack on the local host. There is not any exploit available.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 7.1.8 and classified as problematic. Affected by this vulnerability is the function __bpf_nf_ct_lookup/__bpf_nf_ct_alloc_entry of the component BPF. The manipulation of the argument opts with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix netns reference imbalance in conntrack kfuncs The opts argument of the BPF conntrack kfuncs can point to a shared map value. __bpf_nf_ct_lookup() and __bpf_nf_ct_alloc_entry() read opts->netns_id separately when acquiring and releasing the network namespace reference. The reference imbalance can occur as follows: CPU 0 CPU 1 read opts->netns_id (-1) skip get_net_ns_by_id() write opts->netns_id (id) read opts->netns_id (id) put_net(net) /* no matching get */ The reverse transition leaks the reference. Repeating the unmatched put can destroy a live namespace and crash later users. The kernel reported: Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef] RIP: 0010:bpf_prog_test_run_xdp+0x52c/0x1700 Call Trace: __sys_bpf+0x1662/0x50c0 __x64_sys_bpf+0x73/0xb0 do_syscall_64+0xf9/0x540 entry_SYSCALL_64_after_hwframe+0x77/0x7f Kernel panic - not syncing: Fatal exception Snapshot every input field of opts with READ_ONCE() before validating or using it. The netns_id snapshot keeps the namespace get/put pair balanced, while the other snapshots keep the remaining options from changing partway through an invocation. The individual reads can still observe an inconsistent combination during a concurrent update, but each selected field value remains stable for that invocation.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-74715 since 08/15/2026. The exploitation appears to be easy. An attack has to be approached locally. The exploitation needs additional levels of successful authentication. Technical details are known, but no exploit is available.

Upgrading to version 7.1.9 eliminates this vulnerability. Applying the patch e5e060eb63d10b41ab60fd955649479d99b38210/fdeba03fea78407a8c52faa99177c9f7f29f90eb is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-64402). 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

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4
• 7.1.5
• 7.1.6
• 7.1.7
• 7.1.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

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

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