{"id":"CVE-2026-98127","title":"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","summary":"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 by…","severity":"medium","vendor":"Linux","product":"Linux","affected":["Linux >= 7fe6fe95b936084dce6eedcc2cccadf96eafae73 < 7c2c69045aa76ccaa7f16f1478eb312130ce4951","Linux >= 7fe6fe95b936084dce6eedcc2cccadf96eafae73 < bc7602b9082ef195d913c4c16fa9853dd262333e","Linux >= 7fe6fe95b936084dce6eedcc2cccadf96eafae73 < f8cbfe3a3fcee7d991fd223f660f3e5df13221cf","Linux >= 7fe6fe95b936084dce6eedcc2cccadf96eafae73 < 1519dc88c87f5346dae0464d7d6da1b6bf1f6e8e","Linux 5.13"],"published":"2026-09-25","updated":"2026-09-30","sourceUpdated":"2026-09-30T14:10:59.253","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98127","references":[{"url":"https://git.kernel.org/stable/c/1519dc88c87f5346dae0464d7d6da1b6bf1f6e8e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7c2c69045aa76ccaa7f16f1478eb312130ce4951","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bc7602b9082ef195d913c4c16fa9853dd262333e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f8cbfe3a3fcee7d991fd223f660f3e5df13221cf","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98127.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-98127"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541317"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98127"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98127"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98127.mbox"},{"url":"https://git.kernel.org/stable/c/b7f2e33d9f5db7b8e6e5e0a5a93d0c5e31870356"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.0013,"epssPercentile":0.02626,"ingestedAt":"2026-09-25T11:06:38.818Z","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-1284"],"slug":"CVE-2026-98127","body":"## Overview\n\nIn 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\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98127.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":224155,"id":"CVE-2026-98127","ts":1792324964514,"field":"cvss","old":null,"new":"5.5"},{"seq":224154,"id":"CVE-2026-98127","ts":1792324964514,"field":"severity","old":"none","new":"medium"}]}