FKIE_CVE-2026-23417
Vulnerability from fkie_nvd - Published: 2026-04-02 12:16 - Updated: 2026-04-24 15:21
Severity ?
Summary
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
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 6.9 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 |
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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 immediates to\nsurvive unblinded into JIT-compiled native code when bpf_jit_harden \u003e= 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."
}
],
"id": "CVE-2026-23417",
"lastModified": "2026-04-24T15:21:51.940",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
}
]
},
"published": "2026-04-02T12:16:21.097",
"references": [
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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"url": "https://git.kernel.org/stable/c/2321a9596d2260310267622e0ad8fbfa6f95378f"
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
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"description": [
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"value": "NVD-CWE-noinfo"
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],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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