CVE-2026-98042

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

bpf: Don't resurrect a scalar id dropped by collect_linked_regs()

check_cond_jmp_op() copies the compared registers into

env->{false,true}_reg{1,2} before collect_linked_regs() runs and copies

those snapshots back into both branch states afterwards.

collect_linked_regs() records at most LINKED_REGS_MAX members of a

linked registers group in the jump history and calls clear_scalar_id()

for every member that does not fit. The compared register is not exempt

from that.

As a consequence, sync_linked_regs() might adjust ranges for more

registers than bpf_bt_sync_linked_regs() can propagate precision to.

Collect the linked registers before the snapshots are taken instead.

This might lead to some unnecessary clear_scalar_id's, but from

previous testing situations with many linked registers are

extremely rare.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References