Medium 5.5Published Apr 2, 2026

CVE-2026-23417bpf: Fix constant blinding for PROBE_MEM32 stores

Updated under an hour ago (Oct 28, 2026, 4:50 AM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix constant blinding for PROBE_MEM32 stores BPF_ST | BPF_PROBE_MEM32 immediate stores are not handled by bpf_jit_blind_insn(), allowing user-controlled 32-bit immediates to survive unblinded into JIT-compiled native code when bpf_jit_harden >= 1. The root cause is that convert_ctx_accesses() rewrites BPF_ST|BPF_MEM to BPF_ST|BPF_PROBE_MEM32 for arena pointer stores during verification, before bpf_jit_blind_constants() runs during JIT compilation. The blinding switch only matches BPF_ST|BPF_MEM (mode 0x60), not BPF_ST|BPF_PROBE_MEM32 (mode 0xa0). The instruction falls through unblinded. Add BPF_ST|BPF_PROBE_MEM32 cases to bpf_jit_blind_insn() alongside the existing BPF_ST|BPF_MEM cases. The blinding transformation is identical: load the blinded immediate into BPF_REG_AX via mov+xor, then convert the immediate store to a register store (BPF_STX). The rewritten STX instruction must preserve the BPF_PROBE_MEM32 mode so the architecture JIT emits the correct arena addressing (R12-based on x86-64). Cannot use the BPF_STX_MEM() macro here because it hardcodes BPF_MEM mode; construct the instruction directly instead.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: May 11, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	6082b6c328b5486da2b356eae94b8b83c98b5565 builds before 56af722756ed82fee2ae5d5b4d04743407506195; from 6082b6c328b5486da2b356eae94b8b83c98b5565 before ccbf29b28b5554f9d65b2fb53b994673ad58b3bf; from 6082b6c328b5486da2b356eae94b8b83c98b5565 before de641ea08f8fff6906e169d2576c2ac54e562fbb; 6082b6c328b5486da2b356eae94b8b83c98b5565 builds before 2321a9596d2260310267622e0ad8fbfa6f95378f	CNA record
linux linux_kernel linux:linux_kernel	from 6.9.1 before 6.12.80; from 6.13 before 6.18.21; from 6.19 before 6.19.11; 6.9; 7.0; 7.0; 7.0; 7.0; and 3 more ranges	NVD

References

References

https://git.kernel.org/stable/c/56af722756ed82fee2ae5d5b4d04743407506195	patch
https://git.kernel.org/stable/c/ccbf29b28b5554f9d65b2fb53b994673ad58b3bf	patch
https://git.kernel.org/stable/c/de641ea08f8fff6906e169d2576c2ac54e562fbb	patch
https://git.kernel.org/stable/c/2321a9596d2260310267622e0ad8fbfa6f95378f	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.