CVE-2025-23150: Linux kernel · ext4: fix off-by-one error in do_split
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1088.95~20.04.1 : patch Linux kernel soon.
Data as of 28 Oct 2026, 11:14 UTC
- Patch
- Available – fixed in 5.15.0-1088.95~20.04.1, 5.15.0-1094.103~20.04.1, 5.15.0-1087.96~20.04.2 +58
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 May 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7655-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-7686-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7711-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7712-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: ext4: fix off-by-one error in do_split Syzkaller detected a use-after-free issue in ext4_insert_dentry that was caused by out-of-bounds access due to incorrect splitting in do_split. BUG: KASAN: use-after-free in ext4_insert_dentry+0x36a/0x6d0 fs/ext4/namei.c:2109 Write of size 251 at addr ffff888074572f14 by task syz-executor335/5847 CPU: 0 UID: 0 PID: 5847 Comm: syz-executor335 Not tainted 6.12.0-rc6-syzkaller-00318-ga9cda7c0ffed #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106 ext4_insert_dentry+0x36a/0x6d0 fs/ext4/namei.c:2109 add_dirent_to_buf+0x3d9/0x750 fs/ext4/namei.c:2154 make_indexed_dir+0xf98/0x1600 fs/ext4/namei.c:2351 ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2455 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2796 ext4_symlink+0x920/0xb50 fs/ext4/namei.c:3431 vfs_symlink+0x137/0x2e0 fs/namei.c:4615 do_symlinkat+0x222/0x3a0 fs/namei.c:4641 __do_sys_symlink fs/namei.c:4662 [inline] __se_sys_symlink fs/namei.c:4660 [inline] __x64_sys_symlink+0x7a/0x90 fs/namei.c:4660 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> The following loop is located right above 'if' statement. for (i = count-1; i >= 0; i--) { /* is more than half of this entry in 2nd half of the block? */ if (size + map[i].size/2 > blocksize/2) break; size += map[i].size; move++; } 'i' in this case could go down to -1, in which case sum of active entries wouldn't exceed half the block size, but previous behaviour would also do split in half if sum would exceed at the very last block, which in case of having too many long name files in a single block could lead to out-of-bounds access and following use-after-free. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
References
- ubuntu.com/security/CVE-2025-23150 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-23150 (opens in a new tab)
- git.kernel.org/linus/94824ac9a8aaf2fb3c54b4bdde842db80ffa555d (opens in a new tab)
- git.kernel.org/stable/c/16d9067f00e3a7d1df7c3aa9c20d214923d27e10 (opens in a new tab)
- git.kernel.org/stable/c/17df39f455f1289319d4d09e4826aa46852ffd17 (opens in a new tab)
- git.kernel.org/stable/c/2883e9e74f73f9265e5f8d1aaaa89034b308e433 (opens in a new tab)
- git.kernel.org/stable/c/2eeb1085bf7bd5c7ba796ca4119925fa5d336a3f (opens in a new tab)
- git.kernel.org/stable/c/35d0aa6db9d93307085871ceab8a729594a98162 (opens in a new tab)
- git.kernel.org/stable/c/515c34cff899eb5dae6aa7eee01c1295b07d81af (opens in a new tab)
- git.kernel.org/stable/c/94824ac9a8aaf2fb3c54b4bdde842db80ffa555d (opens in a new tab)
- git.kernel.org/stable/c/ab0cc5c25552ae0d20eae94b40a93be11b080fc5 (opens in a new tab)
- git.kernel.org/stable/c/b96bd2c3db26ad0daec5b78c85c098b53900e2e1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7594-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7655-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7654-4 (opens in a new tab)