{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-90043", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.783Z", "datePublished": "2026-09-16T10:33:40.907Z", "dateUpdated": "2026-10-19T08:57:01.055Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:57:01.055Z" }, "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": { "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 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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/block/zram/zram_drv.c", "drivers/block/zram/zram_drv.h" ], "versions": [ { "version": "2e8ff2f51dde73a26b94aed2df4827177bd25e6e", "lessThan": "052b6b2d5fe97547bd2cdb73fa894f6cfea68b11", "status": "affected", "versionType": "git" }, { "version": "2e8ff2f51dde73a26b94aed2df4827177bd25e6e", "lessThan": "a8b5875741d416703e19ad8eeac6fce8a12bd6e4", "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/block/zram/zram_drv.c", "drivers/block/zram/zram_drv.h" ], "versions": [ { "version": "7.0", "status": "affected" }, { "version": "0", "lessThan": "7.0", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.5", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "7.0", "versionEndExcluding": "7.2.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0", "versionEndExcluding": "7.3" } ] } ] } ], "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" } } } }