CVE-2026-72426

A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) subsystem. The __clean_func_state() function, which manages stack slot cleanup, incorrectly clears metadata for pointer spills. This allows a subsequent read from a partially live stack slot to bypass crucial non-scalar register-fill checks, treating a pointer as a scalar value. This vulnerability could lead to a security bypass, potentially enabling information disclosure or other memory corruption issues.

A moderate-impact flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) verifier. The __clean_func_state() routine cleans dead stack slots in 4-byte halves; when the high half of a STACK_SPILL slot holding a pointer is dead and the low half remains live, the cleanup incorrectly clears the saved pointer-spill metadata. A subsequently loaded crafted BPF program can then perform a 32-bit read from the still-live half that bypasses the normal non-scalar register-fill check and is treated as an ordinary scalar stack read. This type confusion in the verifier is a security bypass that could allow an attacker with the ability to load BPF programs on a local system to cause information disclosure or memory corruption. Red Hat Product Security rates this flaw Moderate severity (CVSS 3.1 score 5.5; AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), which is lower than the CVE.org score of 8.4 because exploitation requires local access and the privilege to load BPF programs, and Red Hat's scoring reflects availability impact only. The vulnerable code was introduced in a recent upstream kernel release and is not present in the kernel packages shipped in Red Hat Enterprise Linux 6, 7, 8, 9, and 10 or Red Hat In-Vehicle OS, so these products are not affected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.