CVE-2026-98033

/// Technical description

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

bpf: Preserve inner map identity in callback frames

Callback frame constructors initialize map-typed argument registers with

__mark_reg_known_zero() and then restore map_ptr. This clears map_uid,

which is the only field distinguishing inner maps that share an

inner_map_meta template.

When a timer callback invokes bpf_for_each_map_elem() on a second inner

map, both the saved first map and the second map value can reach the nested

callback as the same template with map_uid zero. bpf_timer_init() then

accepts pairing the timer from the second map with the first map.

The runtime records the first map in the timer without taking a reference.

Freeing that map does not find the timer stored in the second map, so a

later timer callback dereferences the freed map.

Copy map_uid from the same caller register as map_ptr when constructing

for-each, timer/workqueue, and task-work callback arguments. The existing

identity check

/// 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