CVE-2026-89984
In the Linux kernel, the following vulnerability has been resolved:
perf/x86/intel: Fix kernel address leakages in LBR stack
Before Arch LBR gained CPL filtering support, a user-only branch stack could still contain kernel addresses. As a result, kernel branch records may be exposed to user space even when PERF_SAMPLE_BRANCH_USER is requested.
For example, on Intel Tiger Lake, the following command can still report SYSRET/ERET entries with kernel-space from addresses:
0.219000 usecs/op 4,566,210 ops/sec [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.551 MB - ] 0xffffffff93c001c8/0x7f12a2b1d647/P/-/-/16959/SYSRET/- 0xffffffff93c001c8/0x7f12a2b1d5c2/P/-/-/17535/SYSRET/- 0xffffffff93c01928/0x7f12a2861000/P/-/-/6719/ERET/- 0xffffffff93c01928/0x7f12a297a000/P/-/-/8575/ERET/-
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The problem is that intel_pmu_lbr_filter() does not fully validate the privilege level of sampled entries. It filters some mismatches based on the branch type and the to address, but it does not reject entries whose from address violates the requested branch privilege filter.
Fix this by extending software filtering to validate both from and to addresses against br_sel. Any LBR entry contains kernel address does not match the requested user filter is dropped. This prevents kernel addresses from appearing in user-only branch stacks.
Detalles técnicos trazas, registros y código del informe original
$ ./perf record -e cycles:p -o - --branch-filter any,save_type,u -- \
./perf bench syscall basic --loop 1000 | \
./perf script -i - --fields brstack|tr ' ' '\n'| \
grep -E '0x[89a-f][0-9a-f]{15}'
Total time: 0.000 [sec]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: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 4/10/2026
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/3c492c8eba02698ca893a9a13388d2adf6dfb839
- https://git.kernel.org/stable/c/68c4b780b266a435261a1e029bede5ee3c2735cc
- https://git.kernel.org/stable/c/6ac26161db27f7fb9d9e89ae240dbe52795496cc
- https://git.kernel.org/stable/c/b589147f54adc62e4172e4acf079ad5fb7b3687f
- https://git.kernel.org/stable/c/be0628a101ac05b085aaa4f650d48bd3915e80fa
- https://git.kernel.org/stable/c/ca19a175e89b7de604fab736436cbab74030b47a
- https://git.kernel.org/stable/c/e2b0575900ff72aa82748af96e7bd564ade5157a
- https://git.kernel.org/stable/c/f3705db4e6378cc1b91a38ce0fe2f879055e23ca
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-89984",
"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": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "f3705db4e6378cc1b91a38ce0fe2f879055e23ca",
"versionType": "git"
},
{
"status": "affected",
"version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "b589147f54adc62e4172e4acf079ad5fb7b3687f",
"versionType": "git"
},
{
"status": "affected",
"version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "be0628a101ac05b085aaa4f650d48bd3915e80fa",
"versionType": "git"
},
{
"status": "affected",
"version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "ca19a175e89b7de604fab736436cbab74030b47a",
"versionType": "git"
},
{
"status": "affected",
"version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "6ac26161db27f7fb9d9e89ae240dbe52795496cc",
"versionType": "git"
},
{
"status": "affected",
"version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "3c492c8eba02698ca893a9a13388d2adf6dfb839",
"versionType": "git"
},
{
"status": "affected",
"version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "68c4b780b266a435261a1e029bede5ee3c2735cc",
"versionType": "git"
},
{
"status": "affected",
"version": "47125db27e47e9d44c878bf8925aa057824bb0d5",
"lessThan": "e2b0575900ff72aa82748af96e7bd564ade5157a",
"versionType": "git"
}
],
"programFiles": [
"arch/x86/events/intel/lbr.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.9"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.9",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.270",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.221",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.188",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.110",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.51",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.5",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/x86/events/intel/lbr.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-16T11:17:09.403",
"references": [
{
"url": "https://git.kernel.org/stable/c/3c492c8eba02698ca893a9a13388d2adf6dfb839",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/68c4b780b266a435261a1e029bede5ee3c2735cc",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/6ac26161db27f7fb9d9e89ae240dbe52795496cc",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/b589147f54adc62e4172e4acf079ad5fb7b3687f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/be0628a101ac05b085aaa4f650d48bd3915e80fa",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/ca19a175e89b7de604fab736436cbab74030b47a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e2b0575900ff72aa82748af96e7bd564ade5157a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f3705db4e6378cc1b91a38ce0fe2f879055e23ca",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel: Fix kernel address leakages in LBR stack\n\nBefore Arch LBR gained CPL filtering support, a user-only branch stack\ncould still contain kernel addresses. As a result, kernel branch records\nmay be exposed to user space even when PERF_SAMPLE_BRANCH_USER is\nrequested.\n\nFor example, on Intel Tiger Lake, the following command can still report\nSYSRET/ERET entries with kernel-space from addresses:\n\n$ ./perf record -e cycles:p -o - --branch-filter any,save_type,u -- \\\n \t./perf bench syscall basic --loop 1000 | \\\n\t./perf script -i - --fields brstack|tr ' ' '\\n'| \\\n\tgrep -E '0x[89a-f][0-9a-f]{15}'\n\n Total time: 0.000 [sec]\n\n 0.219000 usecs/op\n 4,566,210 ops/sec\n[ perf record: Woken up 1 times to write data ]\n[ perf record: Captured and wrote 0.551 MB - ]\n0xffffffff93c001c8/0x7f12a2b1d647/P/-/-/16959/SYSRET/-\n0xffffffff93c001c8/0x7f12a2b1d5c2/P/-/-/17535/SYSRET/-\n0xffffffff93c01928/0x7f12a2861000/P/-/-/6719/ERET/-\n0xffffffff93c01928/0x7f12a297a000/P/-/-/8575/ERET/-\n\nThe problem is that intel_pmu_lbr_filter() does not fully validate the\nprivilege level of sampled entries. It filters some mismatches based on\nthe branch type and the to address, but it does not reject entries whose\nfrom address violates the requested branch privilege filter.\n\nFix this by extending software filtering to validate both from and to\naddresses against br_sel. Any LBR entry contains kernel address does not\nmatch the requested user filter is dropped. This prevents kernel\naddresses from appearing in user-only branch stacks."
}
],
"lastModified": "2026-09-16T11:17:09.403",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}