Medium [CVE-2026-53032] Fix NULL deref in map_kptr_match_type for scalar regs
This medium-severity Red Hat Linux advisory covers CVE-2026-53032 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix NULL deref in map_kptr_match_type for scalar regs Commit ab6c637ad027 ("bpf: Fix a bpf_kptr_xchg() issue with local kptr") refactored map_kptr_match_type() to branch on btf_is_kernel() before checking base_type().
A scalar register stored into a kptr slot has no btf, so the btf_is_kernel(reg->btf) call dereferences NULL. Move the base_type()!= PTR_TO_BTF_ID guard before any reg->btf access.
A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) subsystem. This vulnerability occurs in the map_kptr_match_type function when a scalar register is stored into a kernel pointer (kptr) slot.
Due to an incorrect order of checks, the system attempts to access a null pointer, specifically a BPF Type Format (BTF) definition that does not exist for scalar registers. This null pointer dereference can lead to a system crash, resulting in a Denial of Service (DoS).
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-476.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: kernel-rt.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 9 days ago·verify at source
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