CVE-2026-98641
In the Linux kernel, the following vulnerability has been resolved:
bpf, arm64: set up the frame pointer for the exception callback
A program acting as exception boundary saves all callee-saved registers, so build_prologue() takes the exception_cb path and never calls push_callee_regs(). That is the only place find_used_callee_regs() runs, and with it the only place ctx->fp_used is set, so the callback prologue does not emit the
that points BPF_REG_FP at the frame the callback runs on. x25 keeps whatever it held when bpf_throw() was called. If the throw came from a subprogram that uses its own BPF stack, that is the subprogram's frame pointer, and since the subprogram never returns it never restores x25 either.
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Stack accesses through BPF_REG_FP are rewritten to be stack pointer relative, so those still land in the callback's own frame. Materializing the register does not: a callback that passes the address of a local variable to a helper hands over an address in the dead subprogram's frame. That address is below the callback's stack pointer by then, and the helper's own call chain covers it, so the helper can write over its own return address. 0x1234 below is the value the helper was asked to store:
Set ctx->fp_used on the exception callback path so that the existing code further down sets x25 from the stack pointer. The epilogue restores it from the main program's save area along with the other callee-saved registers, as it already does. x86 sets the frame pointer for the callback from the argument it is passed, and powerpc computes it from the stack pointer.
Technical details traces, logs and code from the original report
mov x25, sp pc : 0x1234 lr : 0x1234 Call trace: 0x1234 (P) bpf_test_run+0x188/0x3e0 bpf_prog_test_run_skb+0x47c/0x998 __sys_bpf+0xbdc/0xdd8 Kernel panic - not syncing: Oops: Fatal exception in interrupt
CVSS
NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.17 %
- Percentile among all scored CVEs
- 6
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
References
Show 4 references
Raw JSON (NVD)
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{
"id": "CVE-2026-98641",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff",
"lessThan": "ecdd770a9fc3eaf6c3127c5991312b84774a7b0f",
"versionType": "git"
},
{
"status": "affected",
"version": "5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff",
"lessThan": "b67b4c763f211e7a6391c356fef552e2ea63f08a",
"versionType": "git"
},
{
"status": "affected",
"version": "5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff",
"lessThan": "d7cd5ebe13989f265015910faa25e5d50faa4c22",
"versionType": "git"
},
{
"status": "affected",
"version": "5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff",
"lessThan": "ef1fb82f12186dd26153b14d9fbcf4ec98db81b3",
"versionType": "git"
}
],
"programFiles": [
"arch/arm64/net/bpf_jit_comp.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.12",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.55",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.9",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/arm64/net/bpf_jit_comp.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:17.247",
"references": [
{
"url": "https://git.kernel.org/stable/c/b67b4c763f211e7a6391c356fef552e2ea63f08a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d7cd5ebe13989f265015910faa25e5d50faa4c22",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/ecdd770a9fc3eaf6c3127c5991312b84774a7b0f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/ef1fb82f12186dd26153b14d9fbcf4ec98db81b3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, arm64: set up the frame pointer for the exception callback\n\nA program acting as exception boundary saves all callee-saved registers,\nso build_prologue() takes the exception_cb path and never calls\npush_callee_regs(). That is the only place find_used_callee_regs() runs,\nand with it the only place ctx->fp_used is set, so the callback prologue\ndoes not emit the\n\n mov x25, sp\n\nthat points BPF_REG_FP at the frame the callback runs on. x25 keeps\nwhatever it held when bpf_throw() was called. If the throw came from a\nsubprogram that uses its own BPF stack, that is the subprogram's frame\npointer, and since the subprogram never returns it never restores x25\neither.\n\nStack accesses through BPF_REG_FP are rewritten to be stack pointer\nrelative, so those still land in the callback's own frame. Materializing\nthe register does not: a callback that passes the address of a local\nvariable to a helper hands over an address in the dead subprogram's\nframe. That address is below the callback's stack pointer by then, and\nthe helper's own call chain covers it, so the helper can write over its\nown return address. 0x1234 below is the value the helper was asked to\nstore:\n\n pc : 0x1234\n lr : 0x1234\n Call trace:\n 0x1234 (P)\n bpf_test_run+0x188/0x3e0\n bpf_prog_test_run_skb+0x47c/0x998\n __sys_bpf+0xbdc/0xdd8\n Kernel panic - not syncing: Oops: Fatal exception in interrupt\n\nSet ctx->fp_used on the exception callback path so that the existing code\nfurther down sets x25 from the stack pointer. The epilogue restores it\nfrom the main program's save area along with the other callee-saved\nregisters, as it already does. x86 sets the frame pointer for the\ncallback from the argument it is passed, and powerpc computes it from\nthe stack pointer."
}
],
"lastModified": "2026-10-19T10:19:28.340",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}