{"id":"CVE-2025-71123","title":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix string copying in parse_apply_sb_mount_options()\n\nstrscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term\nstring of possibly bigger size","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix string copying in parse_apply_sb_mount_options()\n\nstrscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term\nstring of possibly bigger size.  C…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 5.4.301, < 5.5","linux_kernel >= 5.10.246, < 5.10.248","linux_kernel >= 6.1.158, < 6.1.160","linux_kernel >= 6.6.114, < 6.6.120","linux_kernel >= 6.12.54, < 6.12.64","linux_kernel >= 6.17.4, < 6.18","linux_kernel >= 6.18.1, < 6.18.3","linux_kernel = 6.18","linux_kernel = 6.19"],"patched":["linux_kernel 6.18.3"],"published":"2026-01-14","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:18:23.170","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-71123","references":[{"url":"https://git.kernel.org/stable/c/52ac96c4a2dd7bc47666000440b0602d9742e820","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5bbacbbf1ca4419861dca3c6b82707c10e9c021c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6e37143560e37869d51b7d9e0ac61fc48895f8a0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/902ca2356f1e3ec5355c5808ad5d3f9d0095b0cc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/db9ee13fab0267eccf6544ee35b16c9522db9aac","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ee5a977b4e771cc181f39d504426dbd31ed701cc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00171,"epssPercentile":0.06438,"ingestedAt":"2026-09-08T15:33:26.995Z","slug":"CVE-2025-71123","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\next4: fix string copying in parse_apply_sb_mount_options()\n\nstrscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term\nstring of possibly bigger size.  Commit 0efc5990bca5 (\"string.h: Introduce\nmemtostr() and memtostr_pad()\") provides additional information in that\nregard.  So if this happens, the following warning is observed:\n\nstrnlen: detected buffer overflow: 65 byte read of buffer size 64\nWARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032\nModules linked in:\nCPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\nRIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032\nCall Trace:\n <TASK>\n __fortify_panic+0x1f/0x30 lib/string_helpers.c:1039\n strnlen include/linux/fortify-string.h:235 [inline]\n sized_strscpy include/linux/fortify-string.h:309 [inline]\n parse_apply_sb_mount_options fs/ext4/super.c:2504 [inline]\n __ext4_fill_super fs/ext4/super.c:5261 [inline]\n ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706\n get_tree_bdev_flags+0x387/0x620 fs/super.c:1636\n vfs_get_tree+0x93/0x380 fs/super.c:1814\n do_new_mount fs/namespace.c:3553 [inline]\n path_mount+0x6ae/0x1f70 fs/namespace.c:3880\n do_mount fs/namespace.c:3893 [inline]\n __do_sys_mount fs/namespace.c:4103 [inline]\n __se_sys_mount fs/namespace.c:4080 [inline]\n __x64_sys_mount+0x280/0x300 fs/namespace.c:4080\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nSince userspace is expected to provide s_mount_opts field to be at most 63\ncharacters long with the ending byte being NUL-term, use a 64-byte buffer\nwhich matches the size of s_mount_opts, so that strscpy_pad() does its job\nproperly.  Return with error if the user still managed to provide a\nnon-NUL-term string here.\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller.\n\n## Affected\n\n- `linux_kernel >= 5.4.301, < 5.5`\n- `linux_kernel >= 5.10.246, < 5.10.248`\n- `linux_kernel >= 6.1.158, < 6.1.160`\n- `linux_kernel >= 6.6.114, < 6.6.120`\n- `linux_kernel >= 6.12.54, < 6.12.64`\n- `linux_kernel >= 6.17.4, < 6.18`\n- `linux_kernel >= 6.18.1, < 6.18.3`\n- `linux_kernel = 6.18`\n- `linux_kernel = 6.19`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.18.3`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":221587,"id":"CVE-2025-71123","ts":1792035282263,"field":"cvss","old":null,"new":"7.8"},{"seq":221586,"id":"CVE-2025-71123","ts":1792035282263,"field":"severity","old":"none","new":"high"}]}