CVE-2025-37738 ext4: ignore xattrs past end
A use-after-free vulnerability in the Linux kernel ext4 filesystem allows attackers to cause a denial of service or potentially execute code via crafted xattr entries.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-37738?
CVE-2025-37738 is a high-severity use after free vulnerability in Debian Debian Linux, published on 1 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ext4: ignore xattrs past end
Once inside 'ext4_xattr_inode_dec_ref_all' we should ignore xattrs entries past the 'end' entry.
This fixes the following KASAN reported issue:
================================================================== BUG: KASAN: slab-use-after-free in ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 Read of size 4 at addr ffff888012c120c4 by task repro/2065
CPU: 1 UID: 0 PID: 2065 Comm: repro Not tainted 6.13.0-rc2+ #11 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x1fd/0x300 ? tcp_gro_dev_warn+0x260/0x260 ? _printk+0xc0/0x100 ? read_lock_is_recursive+0x10/0x10 ? irq_work_queue+0x72/0xf0 ? __virt_addr_valid+0x17b/0x4b0 print_address_description+0x78/0x390 print_report+0x107/0x1f0 ? __virt_addr_valid+0x17b/0x4b0 ? __virt_addr_valid+0x3ff/0x4b0 ? __phys_addr+0xb5/0x160 ? ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 kasan_report+0xcc/0x100 ? ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 ext4_xattr_inode_dec_ref_all+0xb8c/0xe90 ? ext4_xattr_delete_inode+0xd30/0xd30 ? __ext4_journal_ensure_credits+0x5f0/0x5f0 ? __ext4_journal_ensure_credits+0x2b/0x5f0 ? inode_update_timestamps+0x410/0x410 ext4_xattr_delete_inode+0xb64/0xd30 ? ext4_truncate+0xb70/0xdc0 ? ext4_expand_extra_isize_ea+0x1d20/0x1d20 ? __ext4_mark_inode_dirty+0x670/0x670 ? ext4_journal_check_start+0x16f/0x240 ? ext4_inode_is_fast_symlink+0x2f2/0x3a0 ext4_evict_inode+0xc8c/0xff0 ? ext4_inode_is_fast_symlink+0x3a0/0x3a0 ? do_raw_spin_unlock+0x53/0x8a0 ? ext4_inode_is_fast_symlink+0x3a0/0x3a0 evict+0x4ac/0x950 ? proc_nr_inodes+0x310/0x310 ? trace_ext4_drop_inode+0xa2/0x220 ? _raw_spin_unlock+0x1a/0x30 ? iput+0x4cb/0x7e0 do_unlinkat+0x495/0x7c0 ? try_break_deleg+0x120/0x120 ? 0xffffffff81000000 ? __check_object_size+0x15a/0x210 ? strncpy_from_user+0x13e/0x250 ? getname_flags+0x1dc/0x530 __x64_sys_unlinkat+0xc8/0xf0 do_syscall_64+0x65/0x110 entry_SYSCALL_64_after_hwframe+0x67/0x6f RIP: 0033:0x434ffd Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 8 RSP: 002b:00007ffc50fa7b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000107 RAX: ffffffffffffffda RBX: 00007ffc50fa7e18 RCX: 0000000000434ffd RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000005 RBP: 00007ffc50fa7be0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffc50fa7e08 R14: 00000000004bbf30 R15: 0000000000000001 </TASK>
The buggy address belongs to the object at ffff888012c12000 which belongs to the cache filp of size 360 The buggy address is located 196 bytes inside of freed 360-byte region [ffff888012c12000, ffff888012c12168)
The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12c12 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x40(head|node=0|zone=0) page_type: f5(slab) raw: 0000000000000040 ffff888000ad7640 ffffea0000497a00 dead000000000004 raw: 0000000000000000 0000000000100010 00000001f5000000 0000000000000000 head: 0000000000000040 ffff888000ad7640 ffffea0000497a00 dead000000000004 head: 0000000000000000 0000000000100010 00000001f5000000 0000000000000000 head: 0000000000000001 ffffea00004b0481 ffffffffffffffff 0000000000000000 head: 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff888012c11f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888012c12000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888012c12080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888012c12100: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc ffff888012c12180: fc fc fc fc fc fc fc fc fc ---truncated---
Weakness: CWE-416
Which versions are affected by CVE-2025-37738?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-37738?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-37738 being exploited?
There is no known exploitation of CVE-2025-37738 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-37738, DEBIAN-CVE-2025-37738, GHSA-jw72-qv66-6947, ROOT-OS-DEBIAN-12-CVE-2025-37738, ROOT-OS-UBUNTU-2204-CVE-2025-37738, ROOT-OS-UBUNTU-2404-CVE-2025-37738 and 1 more.