GHSA-7C78-FPCM-VCQR
Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 12:31In the Linux kernel, the following vulnerability has been resolved:
bpf: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge
Nicholas Carlini reported a bug in precision backtracking mechanism for BPF_LD | BPF_{IND,ABS} instructions. These instructions are modelled as two branches: - fallthrough; - implicit exit from current subprogram.
The implicit exit case was not handled by the backtrack_insn() function. When backtracking such a path backtrack_insn() did not call bt_subprog_enter(), which meant that backtracking continued manipulating precision marks in a caller frame, while looking at instructions in a callee frame.
This lead to segmentation faults during verification (see the selftest), or unsound state pruning.
{
"affected": [],
"aliases": [
"CVE-2026-98085"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-25T11:17:38Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge\n\nNicholas Carlini reported a bug in precision backtracking mechanism\nfor BPF_LD | BPF_{IND,ABS} instructions. These instructions are\nmodelled as two branches:\n- fallthrough;\n- implicit exit from current subprogram.\n\nThe implicit exit case was not handled by the backtrack_insn()\nfunction. When backtracking such a path backtrack_insn() did not\ncall bt_subprog_enter(), which meant that backtracking continued\nmanipulating precision marks in a caller frame, while looking at\ninstructions in a callee frame.\n\nThis lead to segmentation faults during verification (see the\nselftest), or unsound state pruning.",
"id": "GHSA-7c78-fpcm-vcqr",
"modified": "2026-09-25T12:31:36Z",
"published": "2026-09-25T12:31:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98085"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/387b1baefbb776e3f48dc2261e77a49213f470f7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/671b7b9a660ef15b25faa3df161205b9dc8d1eb2"
}
],
"schema_version": "1.4.0",
"severity": []
}
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