{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89587","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.729Z","datePublished":"2026-09-11T19:44:52.066Z","dateUpdated":"2026-09-14T12:01:14.959Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-14T12:01:14.959Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nACPI: pfr_update: fix stack buffer overflow in query_capability()\n\nquery_capability() copies four ACPI buffer objects returned by the\nfirmware _DSM into fixed-size u8[16] fields in struct\npfru_update_cap_info using memcpy with the firmware-supplied length:\n\n  memcpy(&cap_hdr->code_type,\n         elements[CAP_CODE_TYPE_IDX].buffer.pointer,\n         elements[CAP_CODE_TYPE_IDX].buffer.length);\n\nThe same pattern repeats for drv_type, platform_id, and oem_id.\nIf the firmware returns buffer.length > 16 for any of these fields,\nmemcpy writes past the destination array.\n\nstruct pfru_update_cap_info is stack-allocated in pfru_ioctl().\n\nConfirmed with KASAN on 7.2-rc6: three stack-out-of-bounds reports\nare generated when a DSM returns 64-byte buffers, with writes reaching\n44 bytes past the end of cap_hdr's [64, 156) frame window into\nadjacent stack redzones.\n\nIntroduce a helper pointer to out_obj->package.elements and use it\nto validate each buffer length against its destination field size\nbefore copying, returning -EINVAL if the firmware supplies an\noversized buffer."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The overflow is reached only via local ioctl(PFRU_IOC_QUERY_CAP) or write() on /dev/acpi_pfr_updateN (pfru_ioctl/pfru_write → query_capability). No network, Bluetooth, USB, or packet path evaluates this ACPI _DSM copy.\nAC:L - A single ioctl or write deterministically copies firmware-supplied _DSM buffer lengths into 16-byte stack fields; KASAN reproduced 64-byte DSM buffers writing 44 bytes past cap_hdr. No race or attacker-uncontrollable memory layout is required.\nPR:L - The ioctl/write path has no capable() or namespace check; access is only DAC on the misc device. Although pfrut checks uid 0 and devtmpfs defaults to 0600, Intel PFRU servers reasonably grant /dev/acpi_pfr_updateN to a firmware-management account or container, so privileges are Low.\nUI:N - The attacker opens the device and issues PFRU_IOC_QUERY_CAP or write() themselves; no separate victim action such as mounting a filesystem or opening a hostile file is required.\nS:U - The overflow corrupts the calling task's kernel stack inside the host kernel. This is local privilege escalation within one security authority, not a VM escape, IOMMU bypass, or sandbox breakout.\nC:H - Firmware-controlled memcpy overflows four u8[16] stack fields and adjacent frame state (KASAN: 44 bytes past cap_hdr), which per kernel guidance is memory corruption leverageable for arbitrary kernel memory disclosure.\nI:H - This is a kernel stack buffer overflow of firmware-controlled length and contents into stack-allocated struct pfru_update_cap_info, overwriting saved registers and the return address and enabling control-flow hijacking.\nA:H - The same out-of-bounds stack writes were confirmed by KASAN and can oops, trip the stack protector, or panic the kernel; the ioctl can be repeated to deny availability."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/acpi/pfr_update.c"],"versions":[{"version":"0db89fa243e5edc5de38c88b369e4c3755c5fb74","lessThan":"d3af83e327565a9444cebc0db714cb837e493046","status":"affected","versionType":"git"},{"version":"0db89fa243e5edc5de38c88b369e4c3755c5fb74","lessThan":"c5a31b4e7e37c92550be9a2edf51ca853a4d251a","status":"affected","versionType":"git"},{"version":"0db89fa243e5edc5de38c88b369e4c3755c5fb74","lessThan":"a2151624b55029dad0ca7efd17fb83a0461c8843","status":"affected","versionType":"git"},{"version":"0db89fa243e5edc5de38c88b369e4c3755c5fb74","lessThan":"6d4ed2fd022bc862b156e53aae163b61259e1caa","status":"affected","versionType":"git"},{"version":"0db89fa243e5edc5de38c88b369e4c3755c5fb74","lessThan":"15d2b7f38f95d28652170344f39ee492c55e567c","status":"affected","versionType":"git"},{"version":"0db89fa243e5edc5de38c88b369e4c3755c5fb74","lessThan":"ced45be0073a8a31b30b4a7f68cd3a15734515de","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/acpi/pfr_update.c"],"versions":[{"version":"5.17","status":"affected"},{"version":"0","lessThan":"5.17","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.109","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.50","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.4","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.17","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/d3af83e327565a9444cebc0db714cb837e493046"},{"url":"https://git.kernel.org/stable/c/c5a31b4e7e37c92550be9a2edf51ca853a4d251a"},{"url":"https://git.kernel.org/stable/c/a2151624b55029dad0ca7efd17fb83a0461c8843"},{"url":"https://git.kernel.org/stable/c/6d4ed2fd022bc862b156e53aae163b61259e1caa"},{"url":"https://git.kernel.org/stable/c/15d2b7f38f95d28652170344f39ee492c55e567c"},{"url":"https://git.kernel.org/stable/c/ced45be0073a8a31b30b4a7f68cd3a15734515de"}],"title":"ACPI: pfr_update: fix stack buffer overflow in query_capability()","x_generator":{"engine":"bippy-1.2.0"}}}}