Bug 2468128 (CVE-2026-43333)

Summary: CVE-2026-43333 kernel: bpf: reject direct access to nullable PTR_TO_BUF pointers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) component. This vulnerability allows a local attacker to cause a kernel null pointer dereference by directly accessing nullable `PTR_TO_BUF` pointers without proper null checks. This can lead to a system crash, resulting in a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-05-08 14:05:53 UTC 
In the Linux kernel, the following vulnerability has been resolved:

bpf: reject direct access to nullable PTR_TO_BUF pointers

check_mem_access() matches PTR_TO_BUF via base_type() which strips
PTR_MAYBE_NULL, allowing direct dereference without a null check.

Map iterator ctx->key and ctx->value are PTR_TO_BUF | PTR_MAYBE_NULL.
On stop callbacks these are NULL, causing a kernel NULL dereference.

Add a type_may_be_null() guard to the PTR_TO_BUF branch, matching the
existing PTR_TO_BTF_ID pattern.
Comment 1 Alexander B 2026-05-15 10:48:05 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-43333.mbox