Linux: Use After Free
CVE-2025-38019 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 f1ecccb5cdda39bca8cd17bb0b6cf61361e33578, abc43c1ffdbc801b0b04ac845bfaf1d42b8f68f7, 9ab7945f3a61ed23da412e30f1e56414c05c4f06 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 0.22% 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 f1ecccb5cdda39bca8cd17bb0b6cf61361e33578 or abc43c1ffdbc801b0b04ac845bfaf1d42b8f68f7 or 9ab7945f3a61ed23da412e30f1e56414c05c4f06 or 92ec4855034b2c4d13f117558dc73d20581fa9ff, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.92 or 6.12.30 or 6.14.8, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 8fdb09a7674c61c4f0e5faf0d63b3ce500a341b0 up to, but not including, f1ecccb5cdda39bca8cd17bb0b6cf61361e33578; 8fdb09a7674c61c4f0e5faf0d63b3ce500a341b0 up to, but not including, abc43c1ffdbc801b0b04ac845bfaf1d42b8f68f7; 8fdb09a7674c61c4f0e5faf0d63b3ce500a341b0 up to, but not including, 9ab7945f3a61ed23da412e30f1e56414c05c4f06; 8fdb09a7674c61c4f0e5faf0d63b3ce500a341b0 up to, but not including, 92ec4855034b2c4d13f117558dc73d20581fa9ff; 6.6 | f1ecccb5cdda39bca8cd17bb0b6cf61361e33578, abc43c1ffdbc801b0b04ac845bfaf1d42b8f68f7, 9ab7945f3a61ed23da412e30f1e56414c05c4f06, 92ec4855034b2c4d13f117558dc73d20581fa9ff |
| Linux | Linux Kernel | 6.6 up to, but not including, 6.6.92; 6.7 up to, but not including, 6.12.30; 6.13 up to, but not including, 6.14.8; 6.15 | 6.6.92, 6.12.30, 6.14.8 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: mlxsw: spectrum_router: Fix use-after-free when deleting GRE net devices The driver only offloads neighbors that are constructed on top of net devices registered by it or their uppers (which are all Ethernet). The device supports GRE encapsulation and decapsulation of forwarded traffic, but the driver will not offload dummy neighbors constructed on top of GRE net devices as they are not uppers of its net devices: # ip link add name gre1 up type gre tos inherit local 192.0.2.1 remote 198.51.100.1 # ip neigh add 0.0.0.0 lladdr 0.0.0.0 nud noarp dev gre1 $ ip neigh show dev gre1 nud noarp 0.0.0.0 lladdr 0.0.0.0 NOARP (Note that the neighbor is not marked with 'offload') When the driver is reloaded and the existing configuration is replayed, the driver does not perform the same check regarding existing neighbors and offloads the previously added one: # devlink dev reload pci/0000:01:00.0 $ ip neigh show dev gre1 nud noarp 0.0.0.0 lladdr 0.0.0.0 offload NOARP If the neighbor is later deleted, the driver will ignore the notification (given the GRE net device is not its upper) and will therefore keep referencing freed memory, resulting in a use-after-free [1] when the net device is deleted: # ip neigh del 0.0.0.0 lladdr 0.0.0.0 dev gre1 # ip link del dev gre1 Fix by skipping neighbor replay if the net device for which the replay is performed is not our upper. [1] BUG: KASAN: slab-use-after-free in mlxsw_sp_neigh_entry_update+0x1ea/0x200 Read of size 8 at addr ffff888155b0e420 by task ip/2282 [...] Call Trace: <TASK> dump_stack_lvl+0x6f/0xa0 print_address_description.constprop.0+0x6f/0x350 print_report+0x108/0x205 kasan_report+0xdf/0x110 mlxsw_sp_neigh_entry_update+0x1ea/0x200 mlxsw_sp_router_rif_gone_sync+0x2a8/0x440 mlxsw_sp_rif_destroy+0x1e9/0x750 mlxsw_sp_netdevice_ipip_ol_event+0x3c9/0xdc0 mlxsw_sp_router_netdevice_event+0x3ac/0x15e0 notifier_call_chain+0xca/0x150 call_netdevice_notifiers_info+0x7f/0x100 unregister_netdevice_many_notify+0xc8c/0x1d90 rtnl_dellink+0x34e/0xa50 rtnetlink_rcv_msg+0x6fb/0xb70 netlink_rcv_skb+0x131/0x360 netlink_unicast+0x426/0x710 netlink_sendmsg+0x75a/0xc20 __sock_sendmsg+0xc1/0x150 ____sys_sendmsg+0x5aa/0x7b0 ___sys_sendmsg+0xfc/0x180 __sys_sendmsg+0x121/0x1b0 do_syscall_64+0xbb/0x1d0 entry_SYSCALL_64_after_hwframe+0x4b/0x53
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
Recent Use After Free vulnerabilities
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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