CVE-2026-90339
In the Linux kernel, the following vulnerability has been resolved:
powerpc/syscall: Fix syscall skip handling for seccomp and ptrace
After enabling GENERIC_ENTRY on PowerPC, syscall_enter_from_user_mode() returns -1 as a sentinel to signal that seccomp or ptrace has intercepted the syscall and already set a return value via syscall_set_return_value(). system_call_exception() was not handling this sentinel, and since -1UL is >= NR_syscalls, the code fell into the out-of-range path and returned -ENOSYS, overwriting the errno already placed in regs->gpr[3].
The naive fix of checking r0 == -1L before the NR_syscalls bounds check is ambiguous: a user legitimately calling syscall(-1) also produces r0 == -1L, and a tracer intercepting such a call would have its injected return value silently discarded.
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Fix this by introducing a thread flag that is set whenever syscall_set_return_value() explicitly updates the return value. In system_call_exception(), check and clear this flag before dispatching the syscall, and return the preset value directly when it is present. This ensures that an explicitly supplied return value always suppresses syscall execution, regardless of the syscall number.
This handles all seccomp actions correctly:
The fix covers both ppc32 and ppc64 with no #ifdefs.
Detalles técnicos trazas, registros y código del informe original
- SECCOMP_RET_ERRNO, SECCOMP_RET_TRACE (no tracer), SECCOMP_RET_USER_NOTIF:
all call syscall_set_return_value(), flag is set, injected value returned.
- SECCOMP_RET_TRAP, SECCOMP_RET_KILL: call syscall_rollback() and deliver
a signal; flag is not set, but the process is dying so the return value
is irrelevant.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: 0.22%
- Percentil entre todas las CVEs puntuadas: 11
- 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
JSON original (NVD)
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{
"id": "CVE-2026-90339",
"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": "bee25f97ad24641df55cb3887eb5bfcb2b9d8fbc",
"lessThan": "19b54740e2e1102c7d48553d9e0347c1f6af22b0",
"versionType": "git"
},
{
"status": "affected",
"version": "bee25f97ad24641df55cb3887eb5bfcb2b9d8fbc",
"lessThan": "69cb2be898be6d5826cacd1a628f6945a24480b6",
"versionType": "git"
}
],
"programFiles": [
"arch/powerpc/include/asm/syscall.h",
"arch/powerpc/include/asm/thread_info.h",
"arch/powerpc/kernel/syscall.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.2"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/powerpc/include/asm/syscall.h",
"arch/powerpc/include/asm/thread_info.h",
"arch/powerpc/kernel/syscall.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-17T17:17:32.520",
"references": [
{
"url": "https://git.kernel.org/stable/c/19b54740e2e1102c7d48553d9e0347c1f6af22b0",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/69cb2be898be6d5826cacd1a628f6945a24480b6",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/syscall: Fix syscall skip handling for seccomp and ptrace\n\nAfter enabling GENERIC_ENTRY on PowerPC, syscall_enter_from_user_mode()\nreturns -1 as a sentinel to signal that seccomp or ptrace has intercepted\nthe syscall and already set a return value via syscall_set_return_value().\nsystem_call_exception() was not handling this sentinel, and since -1UL\nis >= NR_syscalls, the code fell into the out-of-range path and returned\n-ENOSYS, overwriting the errno already placed in regs->gpr[3].\n\nThe naive fix of checking r0 == -1L before the NR_syscalls bounds check\nis ambiguous: a user legitimately calling syscall(-1) also produces r0 ==\n-1L, and a tracer intercepting such a call would have its injected return\nvalue silently discarded.\n\nFix this by introducing a thread flag that is set whenever\nsyscall_set_return_value() explicitly updates the return value. In\nsystem_call_exception(), check and clear this flag before dispatching\nthe syscall, and return the preset value directly when it is present.\nThis ensures that an explicitly supplied return value always suppresses\nsyscall execution, regardless of the syscall number.\n\nThis handles all seccomp actions correctly:\n\n - SECCOMP_RET_ERRNO, SECCOMP_RET_TRACE (no tracer), SECCOMP_RET_USER_NOTIF:\n all call syscall_set_return_value(), flag is set, injected value returned.\n - SECCOMP_RET_TRAP, SECCOMP_RET_KILL: call syscall_rollback() and deliver\n a signal; flag is not set, but the process is dying so the return value\n is irrelevant.\n\nThe fix covers both ppc32 and ppc64 with no #ifdefs."
}
],
"lastModified": "2026-09-17T17:17:32.520",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}