{"cve":"CVE-2025-38415","nvd":{"published":"2025-07-25T14:15:33.250","modified":"2026-06-18T21:16:28.157","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nSquashfs: check return result of sb_min_blocksize\n\nSyzkaller reports an \"UBSAN: shift-out-of-bounds in squashfs_bio_read\" bug.\n\nSyzkaller forks multiple processes which after mounting the Squashfs\nfilesystem, issues an ioctl(\"/dev/loop0\", LOOP_SET_BLOCK_SIZE, 0x8000). \nNow if this ioctl occurs at the same time another process is in the\nprocess of mounting a Squashfs filesystem on /dev/loop0, the failure\noccurs.  When this happens the following code in squashfs_fill_super()\nfails.\n\n----\nmsblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);\nmsblk->devblksize_log2 = ffz(~msblk->devblksize);\n----\n\nsb_min_blocksize() returns 0, which means msblk->devblksize is set to 0.\n\nAs a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2\nis set to 64.\n\nThis subsequently causes the\n\nUBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36\nshift exponent 64 is too large for 64-bit type 'u64' (aka\n'unsigned long long')\n\nThis commit adds a check for a 0 return by sb_min_blocksize().","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-787"],"references":["https://git.kernel.org/stable/c/0aff95d9bc7fb5400ca8af507429c4b067bdb425","https://git.kernel.org/stable/c/295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282","https://git.kernel.org/stable/c/4f99357dadbf9c979ad737156ad4c37fadf7c56b","https://git.kernel.org/stable/c/549f9e3d7b60d53808c98b9fde49b4f46d0524a5","https://git.kernel.org/stable/c/5c51aa862cbeed2f3887f0382a2708956710bd68"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:05:46.678065081+00:00"},"epss":{"cve":"CVE-2025-38415","score":0.00218,"percentile":0.12339,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}