GHSA-3VC4-628M-7F5Q
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-18 18:31In the Linux kernel, the following vulnerability has been resolved:
Squashfs: check block offset is not negative
If a negative offset is read off disk (for example the offset into the decompressed fragment block), this will cause squashfs_copy_data() to perform an out of bounds access.
Fix by checking if offset is negative, and returning 0. This matches existing behaviour where an offset beyond the block returns 0 bytes copied.
To trigger this out of bounds access requires a crafted Squashfs filesystem and CAP_SYS_ADMIN to mount it. Unprivileged users will not be able to mount such a filesystem, but once mounted, an unprivileged user can trigger the out of bounds access by reading the crafted file with the negative offset.
{
"affected": [],
"aliases": [
"CVE-2026-90203"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:15Z",
"severity": "HIGH"
},
"details": "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": "GHSA-3vc4-628m-7f5q",
"modified": "2026-09-18T18:31:27Z",
"published": "2026-09-17T18:31:55Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90203"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3d2f0cb66c909ea2312cdef465165bb9a3ba2d84"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/95dadf366c117dcdca78a570e6832071deab1ecd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b169185d5c672b989985c6c2e38cafab2548ba88"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bbb2218eb072b0a15dc063929200183bd23c2344"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c2a126fca820ae74872da28de68dc74d4595dc4b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d0a3729d464fcf516416a41cf304c0c92126ee03"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e300eb5002925b29be803d2661af07266cfa267e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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