CVE-2026-72426
Description
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.
Statement
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.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 8.4 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability,Integrity,Confidentiality
Technical Impact: Read Memory; Modify Memory; Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart
When a memory buffer is accessed using the wrong type, it could read or write memory out of the bounds of the buffer, if the allocated buffer is smaller than the type that the code is attempting to access, leading to a crash and possibly code execution.
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