Linux: Use After Free
CVE-2026-53262 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 cc19c164a99ab706d4cb45d3c300b305c16798b5, 312ecea13b67797747eb9d4b9dab8d3846de6dfb, 78cdfdca88cbf731a92f3b9ee5427c633dd94e28 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 0.12% 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 cc19c164a99ab706d4cb45d3c300b305c16798b5 or 312ecea13b67797747eb9d4b9dab8d3846de6dfb or 78cdfdca88cbf731a92f3b9ee5427c633dd94e28 or e251d4cdfc725c9e7d686161e3b775a0e7d95053, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.94 or 6.18.36 or 7.0.13, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | fd558d186df2c13a22455373858bae634a4795af up to, but not including, cc19c164a99ab706d4cb45d3c300b305c16798b5; fd558d186df2c13a22455373858bae634a4795af up to, but not including, 312ecea13b67797747eb9d4b9dab8d3846de6dfb; fd558d186df2c13a22455373858bae634a4795af up to, but not including, 78cdfdca88cbf731a92f3b9ee5427c633dd94e28; fd558d186df2c13a22455373858bae634a4795af up to, but not including, e251d4cdfc725c9e7d686161e3b775a0e7d95053; fd558d186df2c13a22455373858bae634a4795af up to, but not including, 62f327e287cf7b595ae3f73ba72f5cd2a9e9f39f; fd558d186df2c13a22455373858bae634a4795af up to, but not including, a213a8950414c684999dcf03edeea6c46ede172e; 2.6.35 | cc19c164a99ab706d4cb45d3c300b305c16798b5, 312ecea13b67797747eb9d4b9dab8d3846de6dfb, 78cdfdca88cbf731a92f3b9ee5427c633dd94e28, e251d4cdfc725c9e7d686161e3b775a0e7d95053, 62f327e287cf7b595ae3f73ba72f5cd2a9e9f39f, a213a8950414c684999dcf03edeea6c46ede172e |
| Linux | Linux Kernel | 2.6.35 up to, but not including, 6.12.94; 6.13 up to, but not including, 6.18.36; 6.19 up to, but not including, 7.0.13; 7.1 | 6.12.94, 6.18.36, 7.0.13 |
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: l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl() pppol2tp_ioctl() read sock->sk->sk_user_data directly without any locks or reference counting. If a controllable sleep was induced during copy_from_user() (e.g. via a userfaultfd page fault sleep), a concurrent socket close could trigger pppol2tp_session_close() asynchronously. This frees the l2tp_session structure via the l2tp_session_del_work workqueue. Upon resuming, the ioctl thread dereferences the stale session pointer, resulting in a Use-After-Free (UAF). Fix this by securely fetching the session reference using the RCU-safe, refcounted helper pppol2tp_sock_to_session(sk) on entry. This locks the session's refcount across the sleep. We structured the function to exit via standard err breaks, guaranteeing that l2tp_session_put() is cleanly called on all return paths to drop the reference. To preserve existing behavior we validate the session and its magic signature only for the specific L2TP commands that require it. This ensures that generic/unknown ioctls called on an unconnected socket still return -ENOIOCTLCMD and correctly fall back to generic handlers (e.g. in sock_do_ioctl()).
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
Other references
Recent Use After Free vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 8.2 High severity
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