{"id":"CVE-2026-89436","title":"platform/x86: panasonic-laptop: Fix sentinel write past pcc->sinf[]","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86: panasonic-laptop: Fix sentinel write past pcc->sinf[]\n\nacpi_pcc_retrieve_biosdata() rejects SINF packages only when\npcc->num_sifr is strictly less than hk…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-787"],"vendor":"Linux","product":"Linux","affected":["Linux >= a3d0dbd18ce908292607bb6cf37c978ece8a33d4 < a93df956ee4d903735b6d395362c839cb1dc07e3","Linux >= a3d0dbd18ce908292607bb6cf37c978ece8a33d4 < 329f10d8be193bf36af124e00b9dd6644cd71724","Linux 7.2"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:46:44.750Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89436","references":[{"url":"https://git.kernel.org/stable/c/a93df956ee4d903735b6d395362c839cb1dc07e3"},{"url":"https://git.kernel.org/stable/c/329f10d8be193bf36af124e00b9dd6644cd71724"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89436.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89436"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532194"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89436"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89436"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89436.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00178,"epssPercentile":0.07364,"scores":{"cna":7.8,"vendor":5.5},"ingestedAt":"2026-09-14T15:23:07.475Z","slug":"CVE-2026-89436","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86: panasonic-laptop: Fix sentinel write past pcc->sinf[]\n\nacpi_pcc_retrieve_biosdata() rejects SINF packages only when\npcc->num_sifr is strictly less than hkey->package.count, then\nunconditionally writes a trailing sentinel at\npcc->sinf[hkey->package.count]. But pcc->sinf[] is allocated with\nexactly pcc->num_sifr elements (valid indices 0..num_sifr-1), so that\nwrite needs num_sifr strictly greater than package.count to stay in\nbounds -- num_sifr == package.count passes the existing check but\nstill overflows by one element.\n\nThis is exactly the case probe()'s existing num_sifr++ workaround\n(\"Some DSDT-s have an off-by-one bug where the SINF package count is\none higher than the SQTY reported value\") is written to accommodate:\nwhen a DSDT's SINF package count equals SQTY+1, the workaround makes\nnum_sifr equal to package.count, which is precisely the boundary that\noverflows here. Found via UBSan (array-index-out-of-bounds) on\nhardware where HKEY.SQTY returns 37 and HKEY.SINF()'s package has 38\nelements: num_sifr becomes 38 after the += 1 workaround, the loop\ncorrectly fills indices 0..37, and the sentinel write then targets\nindex 38, one past the end -- a silent 4-byte heap overflow on kernels\nwithout CONFIG_UBSAN.\n\nTightening the rejection check to num_sifr <= package.count would\navoid the overflow but breaks probe() entirely on exactly this\nhardware, since num_sifr == package.count is the case the off-by-one\nworkaround exists to support. Nothing else in the driver reads this\nsentinel value back, so simply skip the write when there is no room\nfor it instead.\n\n## Affected\n\n- `Linux >= a3d0dbd18ce908292607bb6cf37c978ece8a33d4 < a93df956ee4d903735b6d395362c839cb1dc07e3`\n- `Linux >= a3d0dbd18ce908292607bb6cf37c978ece8a33d4 < 329f10d8be193bf36af124e00b9dd6644cd71724`\n- `Linux 7.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89436.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":224765,"id":"CVE-2026-89436","ts":1792401530380,"field":"cvss","old":"5.5","new":"7.8"},{"seq":224764,"id":"CVE-2026-89436","ts":1792401530380,"field":"severity","old":"medium","new":"high"},{"seq":204122,"id":"CVE-2026-89436","ts":1789490231793,"field":"cvss","old":"4.1","new":"5.5"},{"seq":202913,"id":"CVE-2026-89436","ts":1789403732919,"field":"cvss","old":"7.8","new":"4.1"},{"seq":202912,"id":"CVE-2026-89436","ts":1789403732919,"field":"severity","old":"high","new":"medium"},{"seq":198062,"id":"CVE-2026-89436","ts":1789384321617,"field":"cvss","old":"4.1","new":"7.8"},{"seq":198061,"id":"CVE-2026-89436","ts":1789384321617,"field":"severity","old":"medium","new":"high"},{"seq":183554,"id":"CVE-2026-89436","ts":1789356675863,"field":"cvss","old":"7.8","new":"4.1"},{"seq":183553,"id":"CVE-2026-89436","ts":1789356675863,"field":"severity","old":"high","new":"medium"},{"seq":153218,"id":"CVE-2026-89436","ts":1789285349594,"field":"cvss","old":null,"new":"7.8"},{"seq":153217,"id":"CVE-2026-89436","ts":1789285349594,"field":"severity","old":"none","new":"high"},{"seq":147622,"id":"CVE-2026-89436","ts":1789270211632,"field":"cvss","old":null,"new":"4.1"},{"seq":147621,"id":"CVE-2026-89436","ts":1789270211632,"field":"severity","old":"none","new":"medium"},{"seq":109376,"id":"CVE-2026-89436","ts":1789183731667,"field":"cvss","old":null,"new":"4.1"},{"seq":109375,"id":"CVE-2026-89436","ts":1789183731667,"field":"severity","old":"none","new":"medium"}]}