{"id":"CVE-2026-43166","state":"PUBLISHED","title":"erofs: fix interlaced plain identification for encoded extents","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: fix interlaced plain identification for encoded extents\n\nOnly plain data whose start position and on-disk physical length are\nboth aligned to the block size should be classified as interlaced\nplain extents. Otherwise, it must be treated as shifted plain extents.\n\nThis issue was found by syzbot using a crafted compressed image\ncontaining plain extents with unaligned physical lengths, which can\ncause OOB read in z_erofs_transform_plain().","publishedAt":"2026-05-06T11:27:43.242Z","updatedAt":"2026-08-05T12:26:16.817Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1d191b4ca51d73699cb127386b95ac152af2b930","status":"affected","lessThan":"9d5a97bc71ed5783687705c708454c4453aa91d1","versionType":"git"},{"version":"1d191b4ca51d73699cb127386b95ac152af2b930","status":"affected","lessThan":"d3790f26d38606f020212486359b84632c19d08b","versionType":"git"},{"version":"1d191b4ca51d73699cb127386b95ac152af2b930","status":"affected","lessThan":"4a2d046e4b13202a6301a993961f5b30ae4d7119","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/zmap.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/zmap.c"]}],"references":["https://git.kernel.org/stable/c/9d5a97bc71ed5783687705c708454c4453aa91d1","https://git.kernel.org/stable/c/d3790f26d38606f020212486359b84632c19d08b","https://git.kernel.org/stable/c/4a2d046e4b13202a6301a993961f5b30ae4d7119"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43166.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43166","state":"PUBLISHED","datePublished":"2026-05-06T11:27:43.242Z","dateUpdated":"2026-08-05T12:26:16.817Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:55.990Z"},"containers":{"cna":{"title":"erofs: fix interlaced plain identification for encoded extents","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: fix interlaced plain identification for encoded extents\n\nOnly plain data whose start position and on-disk physical length are\nboth aligned to the block size should be classified as interlaced\nplain extents. Otherwise, it must be treated as shifted plain extents.\n\nThis issue was found by syzbot using a crafted compressed image\ncontaining plain extents with unaligned physical lengths, which can\ncause OOB read in z_erofs_transform_plain()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1d191b4ca51d73699cb127386b95ac152af2b930","status":"affected","lessThan":"9d5a97bc71ed5783687705c708454c4453aa91d1","versionType":"git"},{"version":"1d191b4ca51d73699cb127386b95ac152af2b930","status":"affected","lessThan":"d3790f26d38606f020212486359b84632c19d08b","versionType":"git"},{"version":"1d191b4ca51d73699cb127386b95ac152af2b930","status":"affected","lessThan":"4a2d046e4b13202a6301a993961f5b30ae4d7119","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/zmap.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/erofs/zmap.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9d5a97bc71ed5783687705c708454c4453aa91d1"},{"url":"https://git.kernel.org/stable/c/d3790f26d38606f020212486359b84632c19d08b"},{"url":"https://git.kernel.org/stable/c/4a2d046e4b13202a6301a993961f5b30ae4d7119"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is reached by local VFS operations on a crafted EROFS image: mount the image and read/open a compressed file so EROFS performs readahead/decompression. There is no direct network, adjacent, or physical protocol entry point in EROFS itself.\nAC:L - The trigger is deterministic malformed extent metadata with an aligned physical start and unaligned encoded length; syzbot reproduced it with a crafted image and ordinary mount/open/read activity. No attacker-uncontrolled race or fragile timing condition is required.\nPR:N - An attacker can craft and supply the malicious EROFS image without privileges; the privileged filesystem mount/read can be performed by an interacting victim or image-processing environment. EROFS is not marked FS_USERNS_MOUNT, so a purely self-triggered local mount would require CAP_SYS_ADMIN, but the higher-severity defensible scenario is malicious media/image handling.\nUI:R - Exploitation requires some user or system action to mount or otherwise process the crafted EROFS image and read/open the affected file. The vulnerable code is not reached passively before the image is mounted/read.\nS:U - The bug is in kernel filesystem parsing/decompression and affects the same kernel security authority. It does not cross a hypervisor, VM, IOMMU, or sandbox boundary by itself.\nC:H - The bug causes a slab/out-of-bounds read of up to a page-sized copy in z_erofs_transform_plain(), and the copied bytes are placed into output/page-cache data readable through the file path. This can disclose kernel memory and is not limited to a few fixed bytes.\nI:N - The faulty operation is an out-of-bounds read from the input page mapping followed by copying into the file output page; it does not write out of bounds or corrupt kernel control data. No direct integrity modification primitive is evident.\nA:H - syzbot demonstrated a KASAN slab-out-of-bounds/use-after-free read in this path, and such kernel memory-safety faults can produce an oops/panic on hardened or faulting configurations. The crafted image can retrigger the fault through repeated reads."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:26:16.817Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"6.18.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"6.19.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}