Linux: Use After Free
CVE-2026-53357 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.0 out of 10. It can be exploited from the same local network by an attacker with a low-privileged account, without any action from a user. The record lists versions 751de6ec671fe75ad9cf65a0638d2a06b6a5984d, 407217734835d21d4e0105ebf347860dc1806f88, 7eebd4c2c86f573af87ff165d08a83432eb0b919 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 0.33% 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 751de6ec671fe75ad9cf65a0638d2a06b6a5984d or 407217734835d21d4e0105ebf347860dc1806f88 or 7eebd4c2c86f573af87ff165d08a83432eb0b919 or 5d86d2f1b4d9a508c441d3e45277ae1a73cfed57, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.175 or 6.6.142, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 751de6ec671fe75ad9cf65a0638d2a06b6a5984d; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 407217734835d21d4e0105ebf347860dc1806f88; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 7eebd4c2c86f573af87ff165d08a83432eb0b919; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 5d86d2f1b4d9a508c441d3e45277ae1a73cfed57; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 87c543e2f78d0871f271df92dab98901bbd5b6f5; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, added1213395071470a900cc845a042fb51882a6; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, a5ca86a6097a8b030ca3226cd300b17ed330f966; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, ab1513597c6cf17cd1ad2a21e3b045421b48e022; and 1 more ranges | 751de6ec671fe75ad9cf65a0638d2a06b6a5984d, 407217734835d21d4e0105ebf347860dc1806f88, 7eebd4c2c86f573af87ff165d08a83432eb0b919, 5d86d2f1b4d9a508c441d3e45277ae1a73cfed57, 87c543e2f78d0871f271df92dab98901bbd5b6f5, added1213395071470a900cc845a042fb51882a6 |
| Linux | Linux Kernel | 5.7 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.142; 6.7 up to, but not including, 6.12.92; 6.13 up to, but not including, 6.18.34; 6.19 up to, but not including, 7.0.11; 7.1 | 5.10.259, 5.15.210, 6.1.175, 6.6.142, 6.12.92, 6.18.34 |
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
- AdjacentThe attacker must be on the same local network segment.
- 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:A/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: Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del() bt_accept_dequeue() unlinks a not-yet-accepted child from the parent accept queue and release_sock()s it before returning, so the returned sk has no caller reference and is unlocked. l2cap_sock_cleanup_listen() walks these children on listening-socket close. A concurrent HCI disconnect drives hci_rx_work -> l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and frees the child sk and its l2cap_chan; cleanup_listen() then uses both: BUG: KASAN: slab-use-after-free in l2cap_sock_kill l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill This is distinct from the two fixes already in this area: commit e83f5e24da741 ("Bluetooth: serialize accept_q access") serialises the accept_q list/poll and takes temporary refs inside bt_accept_dequeue(), and CVE-2025-39860 serialises the userspace close()/accept() race by calling cleanup_listen() under lock_sock() in l2cap_sock_release(). Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF still reproduces on current bluetooth/master. Take the reference at the source: bt_accept_dequeue() does sock_hold() while sk is still locked, before release_sock(); callers sock_put(). cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on SOCK_DEAD. conn->lock is not taken here: cleanup_listen() runs under the parent sk lock and that would invert conn->lock -> chan->lock -> sk_lock (lockdep). KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced 12 use-after-free reports per run before this change; 0, and no lockdep report, over 1600+ raced iterations after it on bluetooth/master.
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/407217734835d21d4e0105ebf347860dc1806f88
- git.kernel.org/stable/c/5d86d2f1b4d9a508c441d3e45277ae1a73cfed57
- git.kernel.org/stable/c/751de6ec671fe75ad9cf65a0638d2a06b6a5984d
- git.kernel.org/stable/c/7eebd4c2c86f573af87ff165d08a83432eb0b919
- git.kernel.org/stable/c/87c543e2f78d0871f271df92dab98901bbd5b6f5
- git.kernel.org/stable/c/a5ca86a6097a8b030ca3226cd300b17ed330f966
- git.kernel.org/stable/c/ab1513597c6cf17cd1ad2a21e3b045421b48e022
- git.kernel.org/stable/c/added1213395071470a900cc845a042fb51882a6
Recent Use After Free vulnerabilities
- 8.8 High severity
- 7.5 High severity
- 9.6 Critical severity
- 9.6 Critical severity
- 9.6 Critical severity
- 9.6 Critical severity
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