Linux: Use After Free
CVE-2026-68381 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 dab1493bc9d97947f1219d6823c2e2a28636021b, 0f72fc9659d7f585460d43c158055df5afdcffb6, 793e1c7041b93af96ff87e678329bc16aee7ba88 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 0.49% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to dab1493bc9d97947f1219d6823c2e2a28636021b or 0f72fc9659d7f585460d43c158055df5afdcffb6 or 793e1c7041b93af96ff87e678329bc16aee7ba88 or 6ecb252efa0b413ac3d9979fb4eec247f8fc1258, 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 | 8e6508c7ecb1802909f294827eff38f301d0c937 up to, but not including, dab1493bc9d97947f1219d6823c2e2a28636021b; 09aeab68033161cb54f194da93e51a11aee6144b up to, but not including, 0f72fc9659d7f585460d43c158055df5afdcffb6; a4261bbc33fbf99b99c80aa3a2c5097611802980 up to, but not including, 793e1c7041b93af96ff87e678329bc16aee7ba88; 3aa660c059240e0c795217182cf7df32909dd917 up to, but not including, 6ecb252efa0b413ac3d9979fb4eec247f8fc1258; 3aa660c059240e0c795217182cf7df32909dd917 up to, but not including, 14062c74e5b25c27edcff7a2fe0dc701c930b372; 3aa660c059240e0c795217182cf7df32909dd917 up to, but not including, aa5d8f3f96aa11a4a54ce993c11ce8af11c546f9; f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa; 6.6.84 up to, but not including, 6.6.148; and 3 more ranges | dab1493bc9d97947f1219d6823c2e2a28636021b, 0f72fc9659d7f585460d43c158055df5afdcffb6, 793e1c7041b93af96ff87e678329bc16aee7ba88, 6ecb252efa0b413ac3d9979fb4eec247f8fc1258, 14062c74e5b25c27edcff7a2fe0dc701c930b372, aa5d8f3f96aa11a4a54ce993c11ce8af11c546f9 |
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: pin conn during async oplock break notification smb2_oplock_break_noti() and smb2_lease_break_noti() store a ksmbd_conn pointer in an async ksmbd_work and then queue that work on ksmbd-io. The work only increments conn->r_count, which prevents teardown from passing the pending-request wait after the increment, but it does not pin the struct ksmbd_conn object. If connection teardown races with an oplock break notification, the last conn reference can be dropped before the queued worker finishes. The worker then uses the freed conn in ksmbd_conn_write() and ksmbd_conn_r_count_dec(). Take a real conn reference when publishing the conn pointer to the async work item, and drop it after the notification work has decremented r_count. Apply the same lifetime rule to lease break notification, which uses the same work->conn pattern.
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: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
- git.kernel.org/stable/c/0f72fc9659d7f585460d43c158055df5afdcffb6
- git.kernel.org/stable/c/14062c74e5b25c27edcff7a2fe0dc701c930b372
- git.kernel.org/stable/c/6ecb252efa0b413ac3d9979fb4eec247f8fc1258
- git.kernel.org/stable/c/793e1c7041b93af96ff87e678329bc16aee7ba88
- git.kernel.org/stable/c/aa5d8f3f96aa11a4a54ce993c11ce8af11c546f9
- git.kernel.org/stable/c/dab1493bc9d97947f1219d6823c2e2a28636021b
Recent Use After Free vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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