Linux: Use After Free
CVE-2026-64016 is a critical-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 5e641e4ee0bc1937408d41051a908ad4151be63b, 478bfaa036bd0c7e179acff8b8484bccdee3b8c7, a1a39f227c80cbf369767badc32cba2b225147d1 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 0.67% chance of exploitation within 30 days, higher than 53% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to 5e641e4ee0bc1937408d41051a908ad4151be63b or 478bfaa036bd0c7e179acff8b8484bccdee3b8c7 or a1a39f227c80cbf369767badc32cba2b225147d1 or 6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f0ff7f12398e85b3a11745ff7feab6246f3d75c2 up to, but not including, 5e641e4ee0bc1937408d41051a908ad4151be63b; 4db3dcac84c2f14a45ae201efb38de1fb1bfc009 up to, but not including, 478bfaa036bd0c7e179acff8b8484bccdee3b8c7; ce2e164c1c51c3f7813b80f8c926836e896bcbb3 up to, but not including, a1a39f227c80cbf369767badc32cba2b225147d1; 97a0cd55283b4e63fd92804da91c8d9896adcad9 up to, but not including, 6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3; 1baff47b81f94f9231c91236aa511420d0e266b9 up to, but not including, 3515503322f4819277091839eed46b695096aca5; 6.18.33 up to, but not including, 6.18.34; 7.0.10 up to, but not including, 7.0.11 | 5e641e4ee0bc1937408d41051a908ad4151be63b, 478bfaa036bd0c7e179acff8b8484bccdee3b8c7, a1a39f227c80cbf369767badc32cba2b225147d1, 6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3, 3515503322f4819277091839eed46b695096aca5, 6.18.34 |
| Linux | Linux Kernel | 6.18.33; 7.0.10; 7.1 | Not stated |
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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:N/AC:L/PR:N/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: ksmbd: fix durable reconnect error path file lifetime After a durable reconnect succeeds, ksmbd_reopen_durable_fd() republishes the same ksmbd_file into the session volatile-id table. If smb2_open() then takes a later error path, cleanup first calls ksmbd_fd_put(work, fp) and then unconditionally calls ksmbd_put_durable_fd(dh_info.fp). In this case fp and dh_info.fp are the same object. The first put drops the reconnect lookup reference, but the final durable put can run __ksmbd_close_fd(NULL, fp). Because the final close is not session-aware, it can free the file object without removing the volatile-id entry that was just published into the session table. Use the session-aware put for the final reconnect drop when the reconnect had already succeeded and the error path is cleaning up the republished file. Earlier reconnect failures, before fp is assigned to dh_info.fp, keep using the durable-only put path.
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/3515503322f4819277091839eed46b695096aca5
- git.kernel.org/stable/c/478bfaa036bd0c7e179acff8b8484bccdee3b8c7
- git.kernel.org/stable/c/5e641e4ee0bc1937408d41051a908ad4151be63b
- git.kernel.org/stable/c/6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3
- git.kernel.org/stable/c/a1a39f227c80cbf369767badc32cba2b225147d1
Recent Use After Free vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
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