{"id":"CVE-2026-99018","revision":null,"records":[{"revision":"4f8deada9bc44eae8816edaf86fb9d42","observedAt":"2026-10-24T16:17:04.479+00:00","statement":{"source":"cve-program","id":"CVE-2026-99018","aliases":[],"title":"riscv: entry: gate shadow call stack reload on sstatus.SPP, not tp","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: entry: gate shadow call stack reload on sstatus.SPP, not tp\n\nUnder CONFIG_SHADOW_CALL_STACK, handle_exception() reloads the kernel\nshadow call stack pointer (gp) only when the trap came from userspace.\nIt made that decision with scs_load_current_if_task_changed, which\ncompares the trap-time tp (read back from sscratch into s5) against the\ncurrent tp:\n\n\tbeq\t\\prev, tp, _skip_scs\n\tscs_load_current\n_skip_scs:\n\ntp is a user-writable register.  A user task that sets tp to the\nlinear-map address of its own task_struct (&current) before trapping\nmakes the comparison succeed (can achieve by brute force with KASLR\nenable under our test), so the kernel skips scs_load_current and\nkeeps running with the gp that userspace left in place.  Under\nCONFIG_SHADOW_CALL_STACK gp is the shadow call stack pointer and\nload_global_pointer is a no-op, so the compiler-emitted\n\"sd ra, -8(gp)\" / \"ld ra, -8(gp)\" in every non-leaf function then write\nto, and return through, an attacker-controlled address -- an\nunprivileged kernel arbitrary-write and control-flow-hijack primitive.\nThe poisoned gp is saved to task_struct.scs_sp on return, so the reload\nis skipped on every subsequent entry as well.\n\nDecide \"came from userspace\" from the hardware sstatus.SPP bit (already\nin s1 at this point) instead of from tp, mirroring the check that\nret_from_exception already uses a few instructions later.  SPP is\nwritten by hardware on trap entry and cannot be forged from U-mode.\nLegitimate behaviour is unchanged: user entries (SPP=0) reload the task\nshadow call stack, nested kernel entries (SPP=1) skip it.","state":0,"publishedAt":"2026-10-23T12:20:54.888+00:00","modifiedAt":"2026-10-24T14:10:05.883+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"arch/riscv/include/asm/scs.h\",\n                        \"arch/riscv/kernel/entry.S\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"d1584d791a297aa8ed93503382a682a6ecfc4218\",\n                            \"lessThan\": \"6639735367a7d491977e9e5e7afc50b489d81d83\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d1584d791a297aa8ed93503382a682a6ecfc4218\",\n                            \"lessThan\": \"7d1367a53137e379498eb8791295e58854378636\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d1584d791a297aa8ed93503382a682a6ecfc4218\",\n                            \"lessThan\": \"37b4401ee6fa06046446d55e97e8d11784080843\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d1584d791a297aa8ed93503382a682a6ecfc4218\",\n                            \"lessThan\": \"4d0697f192975dab5985e921989be1d85cf580e9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"arch/riscv/include/asm/scs.h\",\n                        \"arch/riscv/kernel/entry.S\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.7\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.7\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.113\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.57\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.11\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/6639735367a7d491977e9e5e7afc50b489d81d83","https://git.kernel.org/stable/c/7d1367a53137e379498eb8791295e58854378636","https://git.kernel.org/stable/c/37b4401ee6fa06046446d55e97e8d11784080843","https://git.kernel.org/stable/c/4d0697f192975dab5985e921989be1d85cf580e9"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99018","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-99018","identifiers":["CVE-2026-99018"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-10-26T00:46:57.9533087+00:00","complete":true,"records":1756,"lastAttemptAt":"2026-10-26T00:46:57.9533087+00:00","lastSuccessAt":"2026-10-26T00:46:58.1070069+00:00","error":null,"lastVerifiedAt":"2026-10-26T00:46:58.1070087+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-1a687ad2a0b90150aa7d97c9f39e63de695ae2db23e31ebc28df1492c461b23c-8739c76e681f900923b900c9df0ef75cf421d39cabb54650c4b9ad19b6a76d85","complete":true,"records":414048,"lastAttemptAt":"2026-10-26T00:46:56.7781981+00:00","lastSuccessAt":"2026-10-26T00:46:56.7731374+00:00","error":null,"lastVerifiedAt":"2026-10-26T00:46:56.7781981+00:00","snapshotPublishedAt":"2026-10-26T00:42:27+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-43321610382942b8ad8c85917eab1546","complete":false,"records":4735,"lastAttemptAt":"2026-10-26T00:47:02.6516296+00:00","lastSuccessAt":"2026-10-24T23:18:49.862+00:00","error":"InvalidDataException","lastVerifiedAt":"2026-10-24T23:18:49.862+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":4764,"expectedIdentifiers":13474},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-10-26T00:46:57.9533087+00:00","complete":true,"records":1093,"lastAttemptAt":"2026-10-26T00:46:57.9533087+00:00","lastSuccessAt":"2026-10-26T00:46:58.1082168+00:00","error":null,"lastVerifiedAt":"2026-10-26T00:46:58.1082172+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-204a3fb93a00487e8f7f36db01dc851d","complete":true,"records":13413,"lastAttemptAt":"2026-10-26T00:47:00.681998+00:00","lastSuccessAt":"2026-10-25T16:19:28.681+00:00","error":null,"lastVerifiedAt":"2026-10-25T16:19:28.681+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13474,"expectedIdentifiers":13474},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-2375a4e597279abf92e8747e140fe8da9d421877cd49cae3ac69a2cb78469b2c","complete":true,"records":9779,"lastAttemptAt":"2026-10-26T00:46:57.4114497+00:00","lastSuccessAt":"2026-10-24T13:19:53.1346702+00:00","error":null,"lastVerifiedAt":"2026-10-26T00:46:57.4114497+00:00","snapshotPublishedAt":"2026-10-24T03:03:12+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-16ad89dfea13ab9e9b0108e63a759d63bd4559cc68b58491107d62ee35bbbaf2","complete":true,"records":1965,"lastAttemptAt":"2026-10-26T00:46:56.9270949+00:00","lastSuccessAt":"2026-10-23T16:01:26.4487605+00:00","error":null,"lastVerifiedAt":"2026-10-26T00:46:56.9270949+00:00","snapshotPublishedAt":"2026-10-21T12:18:07+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-7da67a15aa6e56a0e3081a7646dc74d537e6ef974afc593c2b1794ed01970648","complete":true,"records":2969,"lastAttemptAt":"2026-10-26T00:46:57.8104847+00:00","lastSuccessAt":"2026-10-24T13:19:59.1145547+00:00","error":null,"lastVerifiedAt":"2026-10-26T00:46:57.8104847+00:00","snapshotPublishedAt":"2026-10-24T08:47:51+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-11236ada05a0588e51df37636716526867f73fb127392c49680b6f8561496a99","complete":true,"records":230781,"lastAttemptAt":"2026-10-26T00:46:57.3095832+00:00","lastSuccessAt":"2026-10-25T22:04:07.173333+00:00","error":null,"lastVerifiedAt":"2026-10-26T00:46:57.3095832+00:00","snapshotPublishedAt":"2026-10-25T21:33:06+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null}]}