{"id":"CVE-2026-23417","title":"bpf: Fix constant blinding for PROBE_MEM32 stores","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix constant blinding for PROBE_MEM32 stores\n\nBPF_ST | BPF_PROBE_MEM32 immediate stores are not handled by\nbpf_jit_blind_insn(), allowing user-controlled 32-bit im…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < 56af722756ed82fee2ae5d5b4d04743407506195","Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < ccbf29b28b5554f9d65b2fb53b994673ad58b3bf","Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < de641ea08f8fff6906e169d2576c2ac54e562fbb","Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < 2321a9596d2260310267622e0ad8fbfa6f95378f","Linux 6.9"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T21:30:20.590529Z"},"published":"2026-04-02","updated":"2026-11-05","sourceUpdated":"2026-11-05T21:33:46.038Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23417","references":[{"url":"https://git.kernel.org/stable/c/56af722756ed82fee2ae5d5b4d04743407506195"},{"url":"https://git.kernel.org/stable/c/ccbf29b28b5554f9d65b2fb53b994673ad58b3bf"},{"url":"https://git.kernel.org/stable/c/de641ea08f8fff6906e169d2576c2ac54e562fbb"},{"url":"https://git.kernel.org/stable/c/2321a9596d2260310267622e0ad8fbfa6f95378f"}],"tags":["cve.org"],"epss":0.00119,"epssPercentile":0.0175,"ingestedAt":"2026-11-05T22:38:32.130Z","slug":"CVE-2026-23417","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix constant blinding for PROBE_MEM32 stores\n\nBPF_ST | BPF_PROBE_MEM32 immediate stores are not handled by\nbpf_jit_blind_insn(), allowing user-controlled 32-bit immediates to\nsurvive unblinded into JIT-compiled native code when bpf_jit_harden >= 1.\n\nThe root cause is that convert_ctx_accesses() rewrites BPF_ST|BPF_MEM\nto BPF_ST|BPF_PROBE_MEM32 for arena pointer stores during verification,\nbefore bpf_jit_blind_constants() runs during JIT compilation. The\nblinding switch only matches BPF_ST|BPF_MEM (mode 0x60), not\nBPF_ST|BPF_PROBE_MEM32 (mode 0xa0). The instruction falls through\nunblinded.\n\nAdd BPF_ST|BPF_PROBE_MEM32 cases to bpf_jit_blind_insn() alongside the\nexisting BPF_ST|BPF_MEM cases. The blinding transformation is identical:\nload the blinded immediate into BPF_REG_AX via mov+xor, then convert\nthe immediate store to a register store (BPF_STX).\n\nThe rewritten STX instruction must preserve the BPF_PROBE_MEM32 mode so\nthe architecture JIT emits the correct arena addressing (R12-based on\nx86-64). Cannot use the BPF_STX_MEM() macro here because it hardcodes\nBPF_MEM mode; construct the instruction directly instead.\n\n## Affected\n\n- `Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < 56af722756ed82fee2ae5d5b4d04743407506195`\n- `Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < ccbf29b28b5554f9d65b2fb53b994673ad58b3bf`\n- `Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < de641ea08f8fff6906e169d2576c2ac54e562fbb`\n- `Linux >= 6082b6c328b5486da2b356eae94b8b83c98b5565 < 2321a9596d2260310267622e0ad8fbfa6f95378f`\n- `Linux 6.9`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}