CVE-2026-90203

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-90203", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.792Z", "datePublished": "2026-09-17T16:07:20.180Z", "dateUpdated": "2026-10-19T08:59:39.333Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:59:39.333Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSquashfs: check block offset is not negative\n\nIf a negative offset is read off disk (for example the offset into the\ndecompressed fragment block), this will cause squashfs_copy_data() to\nperform an out of bounds access.\n\nFix by checking if offset is negative, and returning 0. This matches\nexisting behaviour where an offset beyond the block returns 0 bytes\ncopied.\n\nTo trigger this out of bounds access requires a crafted Squashfs\nfilesystem and CAP_SYS_ADMIN to mount it. Unprivileged users will not be\nable to mount such a filesystem, but once mounted, an unprivileged user\ncan trigger the out of bounds access by reading the crafted file with the\nnegative offset."}], "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 bad bytes are squashfs_reg_inode.offset/squashfs_lreg_inode.offset, stored by squashfs_read_inode() as fragment_offset and used by squashfs_read_folio()/squashfs_readahead_fragment() \u2192 squashfs_copy_data() on a loop/block-backed image. That field is on-disk fragment metadata, not a network protocol message; squashfs_fs_type is FS_REQUIRES_DEV.\nAC:L - squashfs_read_inode() assigns le32_to_cpu(sqsh_ino->offset) to signed int fragment_offset with no range check, so a high-bit-set on-disk value is negative. read() of that file's tail (generic_file_read_iter \u2192 squashfs_read_folio) then calls squashfs_copy_data() with that offset; there is no race.\nPR:N - squashfs_fs_type has no FS_USERNS_MOUNT, so mount_capable() needs init-namespace CAP_SYS_ADMIN, but the attacker who crafts the image needs no account. After that privileged mount, an unprivileged read of the crafted file is enough; the mount is scored as User Interaction, not Privileges Required.\nUI:R - The negative fragment_offset exists only in an attacker-supplied Squashfs image, and squashfs_copy_data() runs only after that image is mounted and the crafted file is read. The mount is the required victim action; a standing snapd or live-image setup does not remove it.\nS:U - squashfs_copy_data() indexes the fragment cache's kmalloc'd data[] array and memcpy's into the file's own page-cache folio in the same kernel. This is not a KVM/Xen guest-to-host escape or an IOMMU/DMA bypass.\nC:H - A negative offset makes squashfs_copy_data() evaluate entry->data[offset/PAGE_SIZE] before the kcalloc'd pointer array, then memcpy up to PAGE_SIZE bytes from that address into the folio returned by read(). That is an unbounded OOB kernel read into userspace, not a few-byte leak.\nI:N - The memcpy destination is the kmap of the crafted file's own folio in squashfs_fill_page()/squashfs_readahead_fragment(); the source is the OOB pointer. Length is capped by avail (\u2264PAGE_SIZE), so this path does not write kernel objects out of bounds.\nA:H - Indexing entry->data[] with a negative offset/PAGE_SIZE and memcpy from the resulting pointer is the same squashfs_copy_data() out-of-bounds access that produced a general protection fault in CVE-2026-23388; an unmapped address oopses the kernel."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/squashfs/cache.c"], "versions": [{"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "b169185d5c672b989985c6c2e38cafab2548ba88", "status": "affected", "versionType": "git"}, {"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "c2a126fca820ae74872da28de68dc74d4595dc4b", "status": "affected", "versionType": "git"}, {"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "95dadf366c117dcdca78a570e6832071deab1ecd", "status": "affected", "versionType": "git"}, {"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "3d2f0cb66c909ea2312cdef465165bb9a3ba2d84", "status": "affected", "versionType": "git"}, {"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "bbb2218eb072b0a15dc063929200183bd23c2344", "status": "affected", "versionType": "git"}, {"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "d0a3729d464fcf516416a41cf304c0c92126ee03", "status": "affected", "versionType": "git"}, {"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe", "status": "affected", "versionType": "git"}, {"version": "f400e12656ab518be107febfe2315fb1eab5a342", "lessThan": "e300eb5002925b29be803d2661af07266cfa267e", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/squashfs/cache.c"], "versions": [{"version": "2.6.29", "status": "affected"}, {"version": "0", "lessThan": "2.6.29", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.110", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.6", "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": "2.6.29", "versionEndExcluding": "5.10.270"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "5.15.221"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.1.188"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.6.157"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.12.110"}, {"vulnerable": true, "criteria": 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"https://git.kernel.org/stable/c/e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe"}, {"url": "https://git.kernel.org/stable/c/e300eb5002925b29be803d2661af07266cfa267e"}], "title": "Squashfs: check block offset is not negative", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/squashfs/cache.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "b169185d5c672b989985c6c2e38cafab2548ba88", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}, {"lessThan": "c2a126fca820ae74872da28de68dc74d4595dc4b", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}, {"lessThan": "95dadf366c117dcdca78a570e6832071deab1ecd", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}, {"lessThan": "3d2f0cb66c909ea2312cdef465165bb9a3ba2d84", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}, {"lessThan": "bbb2218eb072b0a15dc063929200183bd23c2344", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}, {"lessThan": "d0a3729d464fcf516416a41cf304c0c92126ee03", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}, {"lessThan": "e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}, {"lessThan": "e300eb5002925b29be803d2661af07266cfa267e", "status": "affected", "version": "f400e12656ab518be107febfe2315fb1eab5a342", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/squashfs/cache.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "2.6.29"}, {"lessThan": "2.6.29", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.270", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.221", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.188", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.157", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.110", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.52", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.6", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSquashfs: check block offset is not negative\n\nIf a negative offset is read off disk (for example the offset into the\ndecompressed fragment block), this will cause squashfs_copy_data() to\nperform an out of bounds access.\n\nFix by checking if offset is negative, and returning 0. This matches\nexisting behaviour where an offset beyond the block returns 0 bytes\ncopied.\n\nTo trigger this out of bounds access requires a crafted Squashfs\nfilesystem and CAP_SYS_ADMIN to mount it. Unprivileged users will not be\nable to mount such a filesystem, but once mounted, an unprivileged user\ncan trigger the out of bounds access by reading the crafted file with the\nnegative offset."}], "id": "CVE-2026-90203", "lastModified": "2026-10-19T09:19:10.377", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-17T17:17:15.320", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3d2f0cb66c909ea2312cdef465165bb9a3ba2d84"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/95dadf366c117dcdca78a570e6832071deab1ecd"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b169185d5c672b989985c6c2e38cafab2548ba88"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/bbb2218eb072b0a15dc063929200183bd23c2344"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/c2a126fca820ae74872da28de68dc74d4595dc4b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d0a3729d464fcf516416a41cf304c0c92126ee03"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e300eb5002925b29be803d2661af07266cfa267e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,b169185d5c672b989985c6c2e38cafab2548ba88)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,c2a126fca820ae74872da28de68dc74d4595dc4b)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,95dadf366c117dcdca78a570e6832071deab1ecd)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,3d2f0cb66c909ea2312cdef465165bb9a3ba2d84)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,bbb2218eb072b0a15dc063929200183bd23c2344)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,d0a3729d464fcf516416a41cf304c0c92126ee03)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[f400e12656ab518be107febfe2315fb1eab5a342,e300eb5002925b29be803d2661af07266cfa267e)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "2.6.29"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,2.6.29)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.10.270,5.11.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[5.15.221,5.16.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.188,6.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.157,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.110,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.52,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.6,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-18T19:00:06.699990+00:00", "updated": "2026-09-20T01:30:16.548443+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"], "weaknesses": ["CWE-125", "CWE-190"]}