CVE-2026-68295

Received Received - Intake

LoongArch BPF ALU32 Div/Mod Sign Extension Issue

Publication date: 2026-08-10

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: LoongArch: BPF: Zero-extend signed ALU32 div/mod results ALU32 operations write a 32-bit result and leave the upper 32 bits of the BPF register zero. The LoongArch JIT sign-extends the result of signed ALU32 BPF_DIV and BPF_MOD (off=1), so a negative 32-bit quotient or remainder leaves bits 63:32 set in JITted code while the verifier and interpreter model those bits as zero. Keep sign-extension on the operands, which signed divide needs, and zero-extend the ALU32 result after the divide or modulo instruction, matching the unsigned ALU32 div/mod paths and every other ALU32 operation in this JIT.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-10

Last Modified

2026-08-17

Generated

2026-08-30

AI Q&A

2026-08-10

EPSS Evaluated

2026-08-29

NVD

CVE-2026-68295

EUVD

EUVD-2026-55396

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability affects the Linux kernel's BPF (Berkeley Packet Filter) implementation on LoongArch architecture. It involves incorrect handling of signed division and modulo operations in ALU32 instructions. The JIT compiler sign-extends results of these operations, leaving upper bits set, while the verifier expects them to be zero. This mismatch can lead to incorrect behavior in BPF programs.

Detection Guidance

This vulnerability is specific to the Linux kernel's BPF implementation on LoongArch architecture. Detection requires checking kernel version and BPF JIT status. Use uname -a to verify kernel version and grep BPF_JIT /proc/cpuinfo to check if BPF JIT is enabled. If kernel version is vulnerable and BPF JIT is active, the system may be affected.

Impact Analysis

If exploited, this vulnerability could allow a malicious BPF program to bypass security checks or cause unexpected behavior in the kernel. This might lead to privilege escalation, denial of service, or data leaks. Systems running vulnerable LoongArch kernels with BPF enabled are at risk.

Compliance Impact

This vulnerability affects compliance with standards and regulations like GDPR and HIPAA only if the affected system processes personal or sensitive data using BPF programs on LoongArch architecture. The issue could lead to incorrect data handling in kernel-level operations, potentially violating integrity or confidentiality requirements.

Mitigation Strategies

Update the Linux kernel to the latest patched version. Disable BPF JIT if not required by setting bpf_jit_enable=0 in kernel parameters. Monitor vendor advisories for LoongArch-specific patches. Restrict unprivileged BPF usage via kernel parameters like unprivileged_bpf_disabled=1.

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