bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR_CVE-2026-31413

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR\n\nmaybe_fork_scalars() is called for both BPF_AND and BPF_OR when the\nsource operand is a constant.  When dst has signed range [-1, 0], it\nforks the verifier state: the pushed path gets dst = 0, the current\npath gets dst = -1.\n\nFor BPF_AND this is correct: 0 & K == 0.\nFor BPF_OR this is wrong:    0 | K == K, not 0.\n\nThe pushed path therefore tracks dst as 0 when the runtime value is K,\nproducing an exploitable verifier/runtime divergence that allows\nout-of-bounds map access.\n\nFix this by passing env->insn_idx (instead of env->insn_idx + 1) to\npush_stack(), so the pushed path re-executes the ALU instruction with\ndst = 0 and naturally computes the correct result for any opcode.",
    "published": "2026-04-12T05:36:14.632Z",
    "modified": "2026-04-27T14:02:58.059Z",
    "type": "cve",
    "title": "bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/342aa1ee995ef5bbf876096dc3a5e51218d76fa4\nhttps://git.kernel.org/stable/c/58bd87d0e69204dbd739e4387a1edb0c4b1644e7\nhttps://git.kernel.org/stable/c/d13281ae7ea8902b21d99d10a2c8caf0bdec0455\nhttps://git.kernel.org/stable/c/c845894ebd6fb43226b3118d6b017942550910c5",
    "id": "CVE-2026-31413",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux dea9989a3f3961faede93752cd81eb5a9514d911\nLinux Linux 4c122e8ae14950cf6b59d208fc5160f7c601e746\nLinux Linux e52567173ba86dbffb990595fbe60e2e83899372\nLinux Linux bffacdb80b93b7b5e96b26fad64cc490a6c7d6c7\nLinux Linux 6.12.75\nLinux Linux 6.18.16\nLinux Linux 6.19.6",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "dea9989a3f3961faede93752cd81eb5a9514d911",
    "vendor": "Linux",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}