{"api_version":"1","generated_at":"2026-09-16T16:13:56+00:00","cve":"CVE-2026-90043","urls":{"html":"https://cve.report/CVE-2026-90043","api":"https://cve.report/api/cve/CVE-2026-90043.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90043","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90043"},"summary":{"title":"zram: fix slot lock bit position on big-endian 64-bit","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nzram: fix slot lock bit position on big-endian 64-bit\n\nThe slot lock is a bit operation on the whole __lock word, which flags and\nac_time alias as two u32s.  On little-endian the lock bit lands in the\nposition ZRAM_ENTRY_LOCK reserves in flags, so the aliasing works out.  On\n64-bit big-endian it lands in ac_time instead: with\nZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time from\nmark_slot_accessed() or slot_free() wipes out the held lock bit, letting\nanother CPU take the same slot lock; an access time value with that bit\nset makes the slot look locked forever.\n\nShift the lock bit into the flags half of the word on big-endian 64-bit.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-16 11:17:17","updated_at":"2026-09-16 15:18:26"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/a8b5875741d416703e19ad8eeac6fce8a12bd6e4","name":"https://git.kernel.org/stable/c/a8b5875741d416703e19ad8eeac6fce8a12bd6e4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/052b6b2d5fe97547bd2cdb73fa894f6cfea68b11","name":"https://git.kernel.org/stable/c/052b6b2d5fe97547bd2cdb73fa894f6cfea68b11","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90043","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90043","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2e8ff2f51dde73a26b94aed2df4827177bd25e6e 052b6b2d5fe97547bd2cdb73fa894f6cfea68b11 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2e8ff2f51dde73a26b94aed2df4827177bd25e6e a8b5875741d416703e19ad8eeac6fce8a12bd6e4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.5 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/block/zram/zram_drv.c","drivers/block/zram/zram_drv.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"052b6b2d5fe97547bd2cdb73fa894f6cfea68b11","status":"affected","version":"2e8ff2f51dde73a26b94aed2df4827177bd25e6e","versionType":"git"},{"lessThan":"a8b5875741d416703e19ad8eeac6fce8a12bd6e4","status":"affected","version":"2e8ff2f51dde73a26b94aed2df4827177bd25e6e","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/block/zram/zram_drv.c","drivers/block/zram/zram_drv.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.0"},{"lessThan":"7.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.5","versionStartIncluding":"7.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"7.0","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nzram: fix slot lock bit position on big-endian 64-bit\n\nThe slot lock is a bit operation on the whole __lock word, which flags and\nac_time alias as two u32s.  On little-endian the lock bit lands in the\nposition ZRAM_ENTRY_LOCK reserves in flags, so the aliasing works out.  On\n64-bit big-endian it lands in ac_time instead: with\nZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time from\nmark_slot_accessed() or slot_free() wipes out the held lock bit, letting\nanother CPU take the same slot lock; an access time value with that bit\nset makes the slot look locked forever.\n\nShift the lock bit into the flags half of the word on big-endian 64-bit."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The broken slot lock lives in the zram block driver and is reached only through local I/O: zram_submit_bio() for read/write/discard and zram_slot_free_notify() from swap. It is not in a network protocol parser, Bluetooth/WiFi path, or a physical-device driver.\nAC:L - On 64-bit big-endian kernels with CONFIG_ZRAM_TRACK_ENTRY_ACTIME, slot_free() zeros ac_time (the lock bit) immediately after slot_lock(), so exclusion is dropped on every free. An attacker who issues concurrent reads, writes, discards, or swap faults against the same zram page controls both sides of the race.\nPR:L - zram_open() and zram_submit_bio() impose no capability check. In the highest-impact setup zram is already swap or mounted scratch storage, so an unprivileged local user can induce paging or file I/O that hits the slot lock; admin-only device creation is only an environmental prerequisite.\nUI:N - After zram is configured as swap or writable storage, the attacker triggers the vulnerable path directly via memory pressure, page faults, madvise, or ordinary file I/O. No victim must mount a filesystem, open a crafted file, or otherwise participate.\nS:U - Impact is corruption of in-kernel zram table entries and zsmalloc objects on the same host. That is a standard kernel compromise and does not cross a VM, IOMMU, or other separate security authority.\nC:H - Clearing the held slot lock lets one CPU zs_free() a zsmalloc object while another still maps it in read_from_zspool()/zs_obj_read_begin(). That use-after-free of compressed-page heap objects can be reused for arbitrary kernel reads.\nI:H - The same lost exclusion allows double-free of zsmalloc handles and torn updates of slot handle and flags, so a racing writer can free an object another CPU still uses or install a new handle over a live one, enabling arbitrary kernel writes and control-flow hijack.\nA:H - Concurrent zs_free versus zs_obj_read_begin on the same handle can oops or panic the kernel, and an ac_time value that leaves the lock bit set makes later wait_on_bit_lock() sleep uninterruptibly forever on that slot."}]}],"providerMetadata":{"dateUpdated":"2026-09-16T14:41:56.643Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/052b6b2d5fe97547bd2cdb73fa894f6cfea68b11"},{"url":"https://git.kernel.org/stable/c/a8b5875741d416703e19ad8eeac6fce8a12bd6e4"}],"title":"zram: fix slot lock bit position on big-endian 64-bit","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90043","datePublished":"2026-09-16T10:33:40.907Z","dateReserved":"2026-09-11T19:38:34.783Z","dateUpdated":"2026-09-16T14:41:56.643Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-16 11:17:17","lastModifiedDate":"2026-09-16 15:18:26","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90043","Ordinal":"1","Title":"zram: fix slot lock bit position on big-endian 64-bit","CVE":"CVE-2026-90043","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90043","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nzram: fix slot lock bit position on big-endian 64-bit\n\nThe slot lock is a bit operation on the whole __lock word, which flags and\nac_time alias as two u32s.  On little-endian the lock bit lands in the\nposition ZRAM_ENTRY_LOCK reserves in flags, so the aliasing works out.  On\n64-bit big-endian it lands in ac_time instead: with\nZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time from\nmark_slot_accessed() or slot_free() wipes out the held lock bit, letting\nanother CPU take the same slot lock; an access time value with that bit\nset makes the slot look locked forever.\n\nShift the lock bit into the flags half of the word on big-endian 64-bit.","Type":"Description","Title":"zram: fix slot lock bit position on big-endian 64-bit"}]}}}