Linux: Use After Free
CVE-2023-53427 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 275a3d2b9408fc4895e342f772cab9a89960546e, 3524d6da0fe88aee79f06be6572955d16ad76b39, cfd85a0922c4696d768965e686ad805a58d9d834 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.15% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 275a3d2b9408fc4895e342f772cab9a89960546e or 3524d6da0fe88aee79f06be6572955d16ad76b39 or cfd85a0922c4696d768965e686ad805a58d9d834 or 7cbd5bdb5bd4404a5da4309521134b42c65846c0, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.19.276 or 5.4.235 or 5.10.173 or 5.15.99, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c7398583340a6d82b8bb7f7f21edcde27dc6a898 up to, but not including, 275a3d2b9408fc4895e342f772cab9a89960546e; c7398583340a6d82b8bb7f7f21edcde27dc6a898 up to, but not including, 3524d6da0fe88aee79f06be6572955d16ad76b39; c7398583340a6d82b8bb7f7f21edcde27dc6a898 up to, but not including, cfd85a0922c4696d768965e686ad805a58d9d834; c7398583340a6d82b8bb7f7f21edcde27dc6a898 up to, but not including, 7cbd5bdb5bd4404a5da4309521134b42c65846c0; c7398583340a6d82b8bb7f7f21edcde27dc6a898 up to, but not including, 41832c62a75dad530dc5a2856c92ae5459d497e5; c7398583340a6d82b8bb7f7f21edcde27dc6a898 up to, but not including, 2d0c4f5f618f58eba03385363717703bee873c64; c7398583340a6d82b8bb7f7f21edcde27dc6a898 up to, but not including, 3e161c2791f8e661eed24a2c624087084d910215; 4.16 | 275a3d2b9408fc4895e342f772cab9a89960546e, 3524d6da0fe88aee79f06be6572955d16ad76b39, cfd85a0922c4696d768965e686ad805a58d9d834, 7cbd5bdb5bd4404a5da4309521134b42c65846c0, 41832c62a75dad530dc5a2856c92ae5459d497e5, 2d0c4f5f618f58eba03385363717703bee873c64 |
| Linux | Linux Kernel | 4.16 up to, but not including, 4.19.276; 4.20 up to, but not including, 5.4.235; 5.5 up to, but not including, 5.10.173; 5.11 up to, but not including, 5.15.99; 5.16 up to, but not including, 6.1.16; 6.2 up to, but not including, 6.2.3 | 4.19.276, 5.4.235, 5.10.173, 5.15.99, 6.1.16, 6.2.3 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: cifs: Fix warning and UAF when destroy the MR list If the MR allocate failed, the MR recovery work not initialized and list not cleared. Then will be warning and UAF when release the MR: WARNING: CPU: 4 PID: 824 at kernel/workqueue.c:3066 __flush_work.isra.0+0xf7/0x110 CPU: 4 PID: 824 Comm: mount.cifs Not tainted 6.1.0-rc5+ #82 RIP: 0010:__flush_work.isra.0+0xf7/0x110 Call Trace: <TASK> __cancel_work_timer+0x2ba/0x2e0 smbd_destroy+0x4e1/0x990 _smbd_get_connection+0x1cbd/0x2110 smbd_get_connection+0x21/0x40 cifs_get_tcp_session+0x8ef/0xda0 mount_get_conns+0x60/0x750 cifs_mount+0x103/0xd00 cifs_smb3_do_mount+0x1dd/0xcb0 smb3_get_tree+0x1d5/0x300 vfs_get_tree+0x41/0xf0 path_mount+0x9b3/0xdd0 __x64_sys_mount+0x190/0x1d0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 BUG: KASAN: use-after-free in smbd_destroy+0x4fc/0x990 Read of size 8 at addr ffff88810b156a08 by task mount.cifs/824 CPU: 4 PID: 824 Comm: mount.cifs Tainted: G W 6.1.0-rc5+ #82 Call Trace: dump_stack_lvl+0x34/0x44 print_report+0x171/0x472 kasan_report+0xad/0x130 smbd_destroy+0x4fc/0x990 _smbd_get_connection+0x1cbd/0x2110 smbd_get_connection+0x21/0x40 cifs_get_tcp_session+0x8ef/0xda0 mount_get_conns+0x60/0x750 cifs_mount+0x103/0xd00 cifs_smb3_do_mount+0x1dd/0xcb0 smb3_get_tree+0x1d5/0x300 vfs_get_tree+0x41/0xf0 path_mount+0x9b3/0xdd0 __x64_sys_mount+0x190/0x1d0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Allocated by task 824: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 __kasan_kmalloc+0x7a/0x90 _smbd_get_connection+0x1b6f/0x2110 smbd_get_connection+0x21/0x40 cifs_get_tcp_session+0x8ef/0xda0 mount_get_conns+0x60/0x750 cifs_mount+0x103/0xd00 cifs_smb3_do_mount+0x1dd/0xcb0 smb3_get_tree+0x1d5/0x300 vfs_get_tree+0x41/0xf0 path_mount+0x9b3/0xdd0 __x64_sys_mount+0x190/0x1d0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Freed by task 824: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x2a/0x40 ____kasan_slab_free+0x143/0x1b0 __kmem_cache_free+0xc8/0x330 _smbd_get_connection+0x1c6a/0x2110 smbd_get_connection+0x21/0x40 cifs_get_tcp_session+0x8ef/0xda0 mount_get_conns+0x60/0x750 cifs_mount+0x103/0xd00 cifs_smb3_do_mount+0x1dd/0xcb0 smb3_get_tree+0x1d5/0x300 vfs_get_tree+0x41/0xf0 path_mount+0x9b3/0xdd0 __x64_sys_mount+0x190/0x1d0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Let's initialize the MR recovery work before MR allocate to prevent the warning, remove the MRs from the list to prevent the UAF.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/275a3d2b9408fc4895e342f772cab9a89960546e
- git.kernel.org/stable/c/2d0c4f5f618f58eba03385363717703bee873c64
- git.kernel.org/stable/c/3524d6da0fe88aee79f06be6572955d16ad76b39
- git.kernel.org/stable/c/3e161c2791f8e661eed24a2c624087084d910215
- git.kernel.org/stable/c/41832c62a75dad530dc5a2856c92ae5459d497e5
- git.kernel.org/stable/c/7cbd5bdb5bd4404a5da4309521134b42c65846c0
- git.kernel.org/stable/c/cfd85a0922c4696d768965e686ad805a58d9d834
Recent Use After Free vulnerabilities
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