Linux: Use After Free
CVE-2025-68800 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 b957366f5611bbaba03dd10ef861283347ddcc88, 6e367c361a523a4b54fe618215c64a0ee189caf0, 37ca08b35a27ce8fd8e74dd3fd2ae21c23b63b73 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 b957366f5611bbaba03dd10ef861283347ddcc88 or 6e367c361a523a4b54fe618215c64a0ee189caf0 or 37ca08b35a27ce8fd8e74dd3fd2ae21c23b63b73 or 5f2831fc593c2b2efbff7dd0dd7441cec76adcd5, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f38656d067257cc43b652958dd154e1ab0773701 up to, but not including, b957366f5611bbaba03dd10ef861283347ddcc88; f38656d067257cc43b652958dd154e1ab0773701 up to, but not including, 6e367c361a523a4b54fe618215c64a0ee189caf0; f38656d067257cc43b652958dd154e1ab0773701 up to, but not including, 37ca08b35a27ce8fd8e74dd3fd2ae21c23b63b73; f38656d067257cc43b652958dd154e1ab0773701 up to, but not including, 5f2831fc593c2b2efbff7dd0dd7441cec76adcd5; f38656d067257cc43b652958dd154e1ab0773701 up to, but not including, 216afc198484fde110ebeafc017992266f4596ce; f38656d067257cc43b652958dd154e1ab0773701 up to, but not including, 4049a6ace209f4ed150429f86ae796d7d6a4c22b; f38656d067257cc43b652958dd154e1ab0773701 up to, but not including, 8ac1dacec458f55f871f7153242ed6ab60373b90; 5.7 | b957366f5611bbaba03dd10ef861283347ddcc88, 6e367c361a523a4b54fe618215c64a0ee189caf0, 37ca08b35a27ce8fd8e74dd3fd2ae21c23b63b73, 5f2831fc593c2b2efbff7dd0dd7441cec76adcd5, 216afc198484fde110ebeafc017992266f4596ce, 4049a6ace209f4ed150429f86ae796d7d6a4c22b |
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 CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats Cited commit added a dedicated mutex (instead of RTNL) to protect the multicast route list, so that it will not change while the driver periodically traverses it in order to update the kernel about multicast route stats that were queried from the device. One instance of list entry deletion (during route replace) was missed and it can result in a use-after-free [1]. Fix by acquiring the mutex before deleting the entry from the list and releasing it afterwards. [1] BUG: KASAN: slab-use-after-free in mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum] Read of size 8 at addr ffff8881523c2fa8 by task kworker/2:5/22043 CPU: 2 UID: 0 PID: 22043 Comm: kworker/2:5 Not tainted 6.18.0-rc1-custom-g1a3d6d7cd014 #1 PREEMPT(full) Hardware name: Mellanox Technologies Ltd. MSN2010/SA002610, BIOS 5.6.5 08/24/2017 Workqueue: mlxsw_core mlxsw_sp_mr_stats_update [mlxsw_spectrum] Call Trace: <TASK> dump_stack_lvl+0xba/0x110 print_report+0x174/0x4f5 kasan_report+0xdf/0x110 mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum] process_one_work+0x9cc/0x18e0 worker_thread+0x5df/0xe40 kthread+0x3b8/0x730 ret_from_fork+0x3e9/0x560 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 29933: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x8f/0xa0 mlxsw_sp_mr_route_add+0xd8/0x4770 [mlxsw_spectrum] mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum] process_one_work+0x9cc/0x18e0 worker_thread+0x5df/0xe40 kthread+0x3b8/0x730 ret_from_fork+0x3e9/0x560 ret_from_fork_asm+0x1a/0x30 Freed by task 29933: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_save_free_info+0x3b/0x70 __kasan_slab_free+0x43/0x70 kfree+0x14e/0x700 mlxsw_sp_mr_route_add+0x2dea/0x4770 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:444 [mlxsw_spectrum] mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum] process_one_work+0x9cc/0x18e0 worker_thread+0x5df/0xe40 kthread+0x3b8/0x730 ret_from_fork+0x3e9/0x560 ret_from_fork_asm+0x1a/0x30
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: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
- git.kernel.org/stable/c/216afc198484fde110ebeafc017992266f4596ce
- git.kernel.org/stable/c/37ca08b35a27ce8fd8e74dd3fd2ae21c23b63b73
- git.kernel.org/stable/c/4049a6ace209f4ed150429f86ae796d7d6a4c22b
- git.kernel.org/stable/c/5f2831fc593c2b2efbff7dd0dd7441cec76adcd5
- git.kernel.org/stable/c/6e367c361a523a4b54fe618215c64a0ee189caf0
- git.kernel.org/stable/c/8ac1dacec458f55f871f7153242ed6ab60373b90
- git.kernel.org/stable/c/b957366f5611bbaba03dd10ef861283347ddcc88
Recent Use After Free vulnerabilities
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- 7.8 High severity
- 7.8 High severity
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