Linux: Use After Free
CVE-2023-53138 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 68a45c3cf0e2242a533657f4f535d9b6a7447a79, 1793da97a23e31c5bf06631f3f3e5a25f368fd64, 9dc16be373b382ddd4c274052a6e870a95e76c01 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 0.19% 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 68a45c3cf0e2242a533657f4f535d9b6a7447a79 or 1793da97a23e31c5bf06631f3f3e5a25f368fd64 or 9dc16be373b382ddd4c274052a6e870a95e76c01 or c3aaec463a632cf4187dc017e421bfa69d7834a9, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.14.310 or 4.19.278 or 5.4.237 or 5.10.175, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, 68a45c3cf0e2242a533657f4f535d9b6a7447a79; 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, 1793da97a23e31c5bf06631f3f3e5a25f368fd64; 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, 9dc16be373b382ddd4c274052a6e870a95e76c01; 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, c3aaec463a632cf4187dc017e421bfa69d7834a9; 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, 3f14457e1584224f4296af613bbd99deb60b5d91; 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, 287027d8a567168a5d8ce5cb0cba16a34791a48c; 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, d1a11bbdbb5ea9f172019c5a4a3e9d8eabd72179; 7ad65bf68d705b445ef10b77ab50dab22be185ee up to, but not including, 9781e98a97110f5e76999058368b4be76a788484; and 1 more ranges | 68a45c3cf0e2242a533657f4f535d9b6a7447a79, 1793da97a23e31c5bf06631f3f3e5a25f368fd64, 9dc16be373b382ddd4c274052a6e870a95e76c01, c3aaec463a632cf4187dc017e421bfa69d7834a9, 3f14457e1584224f4296af613bbd99deb60b5d91, 287027d8a567168a5d8ce5cb0cba16a34791a48c |
| Linux | Linux Kernel | 3.3 up to, but not including, 4.14.310; 4.15 up to, but not including, 4.19.278; 4.20 up to, but not including, 5.4.237; 5.5 up to, but not including, 5.10.175; 5.11 up to, but not including, 5.15.103; 5.16 up to, but not including, 6.1.20; 6.2 up to, but not including, 6.2.7; 6.3 | 4.14.310, 4.19.278, 5.4.237, 5.10.175, 5.15.103, 6.1.20 |
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 | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: net: caif: Fix use-after-free in cfusbl_device_notify() syzbot reported use-after-free in cfusbl_device_notify() [1]. This causes a stack trace like below: BUG: KASAN: use-after-free in cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138 Read of size 8 at addr ffff88807ac4e6f0 by task kworker/u4:6/1214 CPU: 0 PID: 1214 Comm: kworker/u4:6 Not tainted 5.19.0-rc3-syzkaller-00146-g92f20ff72066 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 cfusbl_device_notify+0x7c9/0x870 net/caif/caif_usb.c:138 notifier_call_chain+0xb5/0x200 kernel/notifier.c:87 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1945 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline] call_netdevice_notifiers net/core/dev.c:1997 [inline] netdev_wait_allrefs_any net/core/dev.c:10227 [inline] netdev_run_todo+0xbc0/0x10f0 net/core/dev.c:10341 default_device_exit_batch+0x44e/0x590 net/core/dev.c:11334 ops_exit_list+0x125/0x170 net/core/net_namespace.c:167 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:594 process_one_work+0x996/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 </TASK> When unregistering a net device, unregister_netdevice_many_notify() sets the device's reg_state to NETREG_UNREGISTERING, calls notifiers with NETDEV_UNREGISTER, and adds the device to the todo list. Later on, devices in the todo list are processed by netdev_run_todo(). netdev_run_todo() waits devices' reference count become 1 while rebdoadcasting NETDEV_UNREGISTER notification. When cfusbl_device_notify() is called with NETDEV_UNREGISTER multiple times, the parent device might be freed. This could cause UAF. Processing NETDEV_UNREGISTER multiple times also causes inbalance of reference count for the module. This patch fixes the issue by accepting only first NETDEV_UNREGISTER notification.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/1793da97a23e31c5bf06631f3f3e5a25f368fd64
- git.kernel.org/stable/c/287027d8a567168a5d8ce5cb0cba16a34791a48c
- git.kernel.org/stable/c/3f14457e1584224f4296af613bbd99deb60b5d91
- git.kernel.org/stable/c/68a45c3cf0e2242a533657f4f535d9b6a7447a79
- git.kernel.org/stable/c/9781e98a97110f5e76999058368b4be76a788484
- git.kernel.org/stable/c/9dc16be373b382ddd4c274052a6e870a95e76c01
- git.kernel.org/stable/c/c3aaec463a632cf4187dc017e421bfa69d7834a9
- git.kernel.org/stable/c/d1a11bbdbb5ea9f172019c5a4a3e9d8eabd72179
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
Spotted an error? Tell us.