{"cve":"CVE-2026-98127","nvd":{"published":"2026-09-25T11:17:44.050","modified":"2026-10-22T15:55:04.660","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb/client: validate new EOF for insert range\n\nsmb3_insert_range() does not check if the new file size\n(i_size + len) is valid. This allows FALLOC_FL_INSERT_RANGE to bypass\nRLIMIT_FSIZE, exceed s_maxbytes, or produce a size outside the loff_t\nrange.\n\nUse check_add_overflow() to calculate the new EOF. Validate it with\ninode_newsize_ok() before modifying the file.\n\nReproducer, using a file on a CIFS mount:\n\n\tbash -c '\n\t\tFILE=/mnt/cifs/repro\n\n\t\ttrap \"\" SIGXFSZ\n\t\tulimit -f 3072\t\t# RLIMIT_FSIZE = 3 MiB\n\n\t\t# A regular write is stopped at 3 MiB.\n\t\tdd if=/dev/zero of=\"$FILE\" bs=1M count=4 status=none\n\t\tstat -c \"size after write: %s\" \"$FILE\"\n\n\t\t# Insert 2 MiB into a 2 MiB file.\n\t\ttruncate -s 2M \"$FILE\"\n\t\tfallocate -i -o 0 -l 2M \"$FILE\"\n\t\tstat -c \"size after insert: %s\" \"$FILE\"\n\t'\n\nBefore this change, the regular write stops at the 3 MiB limit, but\ninsert range grows the file to 4 MiB:\n\n\tdd: error writing '/mnt/cifs/repro': File too large\n\tsize after write: 3145728\n\tsize after insert: 4194304\n\nAfter this change, insert range also fails at the limit and leaves the\n2 MiB file unchanged:\n\n\tdd: error writing '/mnt/cifs/repro': File too large\n\tsize after write: 3145728\n\tfallocate: fallocate failed: File too large\n\tsize after insert: 2097152","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":["CWE-190"],"references":["https://git.kernel.org/stable/c/1519dc88c87f5346dae0464d7d6da1b6bf1f6e8e","https://git.kernel.org/stable/c/7c2c69045aa76ccaa7f16f1478eb312130ce4951","https://git.kernel.org/stable/c/b7f2e33d9f5db7b8e6e5e0a5a93d0c5e31870356","https://git.kernel.org/stable/c/bc7602b9082ef195d913c4c16fa9853dd262333e","https://git.kernel.org/stable/c/f8cbfe3a3fcee7d991fd223f660f3e5df13221cf"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-22T16:41:11.231219466+00:00"},"epss":{"cve":"CVE-2026-98127","score":0.0013,"percentile":0.02624,"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."]}