CVE-2026-97420
Estado: RecibidaSin puntuar—
In the Linux kernel, the following vulnerability has been resolved:
bpf: NUL-terminate replaced sysctl value
When writing to sysctls, proc_sys_call_handler() guarantees that the buffer passed to proc handlers is NUL-terminated. If bpf_sysctl_set_new_value() replaces the pending sysctl value, it can hand a replacement buffer directly to proc handlers. However, the helper currently copies only buf_len bytes into that buffer without appending a NUL terminator, leaving downstream parsers vulnerable to out-of-bounds access.
Fix this by appending a '\0' after the replaced value to restore the expected sysctl semantics. Since the helper already rejects buf_len greater than PAGE_SIZE - 1, there is always room for the extra byte.
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Reproduced in a QEMU x86_64 guest booted with KASAN while exercising the sysctl replacement path with a cgroup/sysctl BPF program. The reproducer targets `/proc/sys/net/core/flow_limit_cpu_bitmap`, fills the original user write buffer with non-zero bytes, and overrides the sysctl value so the replacement buffer lacks a terminating NUL. Under that setup, the pre-fix kernel reported:
Detalles técnicos trazas, registros y código del informe original
BUG: KASAN: slab-out-of-bounds in strnchrnul+0x72/0x90 Read of size 1 at addr ffff88800de57000 by task repro_patch3/66 CPU: 0 UID: 0 PID: 66 Comm: repro_patch3 Not tainted 7.1.0-rc3-00269-g8370ca1f87cc #6 PREEMPT(lazy) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x68/0xa0 print_report+0xcb/0x5e0 ? __virt_addr_valid+0x21d/0x3f0 ? strnchrnul+0x72/0x90 ? strnchrnul+0x72/0x90 kasan_report+0xca/0x100 ? strnchrnul+0x72/0x90 strnchrnul+0x72/0x90 bitmap_parse+0x37/0x2e0 flow_limit_cpu_sysctl+0xc6/0x840 ? __pfx_flow_limit_cpu_sysctl+0x10/0x10 ? __kvmalloc_node_noprof+0x5ba/0x870 proc_sys_call_handler+0x31d/0x480 ? __pfx_proc_sys_call_handler+0x10/0x10 ? selinux_file_permission+0x39f/0x500 ? lock_is_held_type+0x9e/0x120 vfs_write+0x98e/0x1000 ... </TASK> The buggy address is located 0 bytes to the right of allocated 4096-byte region [ffff88800de56000, ffff88800de57000) With this fix applied, rerunning the same sysctl-targeted path yields no corresponding KASAN reports.
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.17%
- Percentil entre todas las CVEs puntuadas: 6
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/31377675c3d75603d957c08e338a9ac27e9f6cd5
- https://git.kernel.org/stable/c/36d3e9f62dc2beb9299d3bb6f589cb9e07f773fe
- https://git.kernel.org/stable/c/3b2814dd842a565fcf9cc370156e1ba9eae16239
- https://git.kernel.org/stable/c/76c14b10f50eb0afcc76e244562fa2d8c661e224
- https://git.kernel.org/stable/c/a66e3b5bacf38d6ab29fa05a9754f7a114485605
- https://git.kernel.org/stable/c/bfcee1f79aaefa90679ad47690107fb7682724ec
- https://git.kernel.org/stable/c/c73e4a04eedc677fe91a736d7a5db45100adba5e
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-97420",
"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": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
"lessThan": "bfcee1f79aaefa90679ad47690107fb7682724ec",
"versionType": "git"
},
{
"status": "affected",
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"lessThan": "c73e4a04eedc677fe91a736d7a5db45100adba5e",
"versionType": "git"
},
{
"status": "affected",
"version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
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"versionType": "git"
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{
"status": "affected",
"version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
"lessThan": "31377675c3d75603d957c08e338a9ac27e9f6cd5",
"versionType": "git"
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{
"status": "affected",
"version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
"lessThan": "76c14b10f50eb0afcc76e244562fa2d8c661e224",
"versionType": "git"
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{
"status": "affected",
"version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
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"versionType": "git"
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{
"status": "affected",
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"lessThan": "a66e3b5bacf38d6ab29fa05a9754f7a114485605",
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],
"programFiles": [
"kernel/bpf/cgroup.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.8"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.8",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.271",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.222",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.111",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"kernel/bpf/cgroup.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-24T17:17:19.853",
"references": [
{
"url": "https://git.kernel.org/stable/c/31377675c3d75603d957c08e338a9ac27e9f6cd5",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/36d3e9f62dc2beb9299d3bb6f589cb9e07f773fe",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/76c14b10f50eb0afcc76e244562fa2d8c661e224",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a66e3b5bacf38d6ab29fa05a9754f7a114485605",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/bfcee1f79aaefa90679ad47690107fb7682724ec",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c73e4a04eedc677fe91a736d7a5db45100adba5e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: NUL-terminate replaced sysctl value\n\nWhen writing to sysctls, proc_sys_call_handler() guarantees that the\nbuffer passed to proc handlers is NUL-terminated. If\nbpf_sysctl_set_new_value() replaces the pending sysctl value, it can\nhand a replacement buffer directly to proc handlers. However, the\nhelper currently copies only buf_len bytes into that buffer without\nappending a NUL terminator, leaving downstream parsers vulnerable to\nout-of-bounds access.\n\nFix this by appending a '\\0' after the replaced value to restore the\nexpected sysctl semantics. Since the helper already rejects buf_len\ngreater than PAGE_SIZE - 1, there is always room for the extra byte.\n\nReproduced in a QEMU x86_64 guest booted with KASAN while exercising\nthe sysctl replacement path with a cgroup/sysctl BPF program. The\nreproducer targets `/proc/sys/net/core/flow_limit_cpu_bitmap`, fills\nthe original user write buffer with non-zero bytes, and overrides the\nsysctl value so the replacement buffer lacks a terminating NUL. Under\nthat setup, the pre-fix kernel reported:\n\n BUG: KASAN: slab-out-of-bounds in strnchrnul+0x72/0x90\n Read of size 1 at addr ffff88800de57000 by task repro_patch3/66\n CPU: 0 UID: 0 PID: 66 Comm: repro_patch3 Not tainted 7.1.0-rc3-00269-g8370ca1f87cc #6 PREEMPT(lazy)\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014\n Call Trace:\n <TASK>\n dump_stack_lvl+0x68/0xa0\n print_report+0xcb/0x5e0\n ? __virt_addr_valid+0x21d/0x3f0\n ? strnchrnul+0x72/0x90\n ? strnchrnul+0x72/0x90\n kasan_report+0xca/0x100\n ? strnchrnul+0x72/0x90\n strnchrnul+0x72/0x90\n bitmap_parse+0x37/0x2e0\n flow_limit_cpu_sysctl+0xc6/0x840\n ? __pfx_flow_limit_cpu_sysctl+0x10/0x10\n ? __kvmalloc_node_noprof+0x5ba/0x870\n proc_sys_call_handler+0x31d/0x480\n ? __pfx_proc_sys_call_handler+0x10/0x10\n ? selinux_file_permission+0x39f/0x500\n ? lock_is_held_type+0x9e/0x120\n vfs_write+0x98e/0x1000\n ...\n </TASK>\n The buggy address is located 0 bytes to the right of\n allocated 4096-byte region [ffff88800de56000, ffff88800de57000)\nWith this fix applied, rerunning the same sysctl-targeted path yields\nno corresponding KASAN reports."
}
],
"lastModified": "2026-10-03T11:17:54.123",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}