{"cve":"CVE-2025-38709","nvd":{"published":"2025-09-04T16:15:39.997","modified":"2026-10-19T21:10:00.160","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nloop: Avoid updating block size under exclusive owner\n\nSyzbot came up with a reproducer where a loop device block size is\nchanged underneath a mounted filesystem. This causes a mismatch between\nthe block device block size and the block size stored in the superblock\ncausing confusion in various places such as fs/buffer.c. The particular\nissue triggered by syzbot was a warning in __getblk_slow() due to\nrequested buffer size not matching block device block size.\n\nFix the problem by getting exclusive hold of the loop device to change\nits block size. This fails if somebody (such as filesystem) has already\nan exclusive ownership of the block device and thus prevents modifying\nthe loop device under some exclusive owner which doesn't expect it.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/139a000d20f2f38ce34296feddd641d730fe1c08","https://git.kernel.org/stable/c/457d2c5e112fd08dc1039b1ae39a83ec1782360d","https://git.kernel.org/stable/c/5d67b30aefeb7a949040bbb1b4e3b84c5d29a624","https://git.kernel.org/stable/c/7e49538288e523427beedd26993d446afef1a6fb","https://git.kernel.org/stable/c/b928438cc87c0bf7ae078e4b7b6e14261e84c5c5"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-38709","score":0.00148,"percentile":0.03963,"date":"2026-10-25"},"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."]}