VulnerabilityPublished 2 Apr 2026Updated 5 Nov 2026

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

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in de641ea08f8fff6906e169d2576c2ac54e562fbb : update Linux kernel when convenient.

Data as of 5 Nov 2026, 22:04 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in de641ea08f8fff6906e169d2576c2ac54e562fbb, ccbf29b28b5554f9d65b2fb53b994673ad58b3bf, 2321a9596d2260310267622e0ad8fbfa6f95378f +1

Exploitation evidence

Disclosed: evidence found.
CVE published 2 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to de641ea08f8fff6906e169d2576c2ac54e562fbb, ccbf29b28b5554f9d65b2fb53b994673ad58b3bf, 2321a9596d2260310267622e0ad8fbfa6f95378f or 56af722756ed82fee2ae5d5b4d04743407506195.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 6082b6c328b5486da2b356eae94b8b83c98b5565, < de641ea08f8fff6906e169d2576c2ac54e562fbb	Fixed in de641ea08f8fff6906e169d2576c2ac54e562fbb
LinuxLinux	Affected ≥ 6082b6c328b5486da2b356eae94b8b83c98b5565, < ccbf29b28b5554f9d65b2fb53b994673ad58b3bf	Fixed in ccbf29b28b5554f9d65b2fb53b994673ad58b3bf
LinuxLinux	Affected ≥ 6082b6c328b5486da2b356eae94b8b83c98b5565, < 2321a9596d2260310267622e0ad8fbfa6f95378f	Fixed in 2321a9596d2260310267622e0ad8fbfa6f95378f
LinuxLinux	Affected ≥ 6082b6c328b5486da2b356eae94b8b83c98b5565, < 56af722756ed82fee2ae5d5b4d04743407506195	Fixed in 56af722756ed82fee2ae5d5b4d04743407506195
LinuxLinux	Affected =6.9	Fixed in–

Description

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.

References

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