Linux: Use After Free
CVE-2026-68290 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 66fd678eef1bc2862bde5e7a0f6106256de74f30, 80fffed08dc1c10e971066941d2daa56253f1552, 16df2d154ec82e2f7e7585b4fa154751ba37729a 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 0.13% 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 66fd678eef1bc2862bde5e7a0f6106256de74f30 or 80fffed08dc1c10e971066941d2daa56253f1552 or 16df2d154ec82e2f7e7585b4fa154751ba37729a or 3aa13fe0c1bb7bc5312f878e61523e5d8cf3f85d, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6f353c2230c199f343406c08482940ec5d8ba89c up to, but not including, 66fd678eef1bc2862bde5e7a0f6106256de74f30; de8d6de0ee27be4b2b1e5b06f04aeacbabbba492 up to, but not including, 80fffed08dc1c10e971066941d2daa56253f1552; 7f5611cbc4871c7fb1ad36c2e5a9edad63dca95c up to, but not including, 16df2d154ec82e2f7e7585b4fa154751ba37729a; 7f5611cbc4871c7fb1ad36c2e5a9edad63dca95c up to, but not including, 3aa13fe0c1bb7bc5312f878e61523e5d8cf3f85d; 7f5611cbc4871c7fb1ad36c2e5a9edad63dca95c up to, but not including, 167e54c703ccd4fa028feb568b0d1002020cff86; 33b3e09a489a31b30342b77cc55290f025d95c7e; 6.12.10 up to, but not including, 6.12.101; 6.6.160 up to, but not including, 6.7; and 1 more ranges | 66fd678eef1bc2862bde5e7a0f6106256de74f30, 80fffed08dc1c10e971066941d2daa56253f1552, 16df2d154ec82e2f7e7585b4fa154751ba37729a, 3aa13fe0c1bb7bc5312f878e61523e5d8cf3f85d, 167e54c703ccd4fa028feb568b0d1002020cff86, 6.12.101 |
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: rds: tcp: unregister sysctl before tearing down listen socket rds_tcp_exit_net() frees the per-netns RDS TCP listen socket via rds_tcp_kill_sock() before unregistering the per-netns sysctl table. Since rds_tcp_skbuf_handler() derives the netns from rtn->rds_tcp_listen_sock->sk, a concurrent sysctl write can race with netns teardown and dereference the freed socket/sk. KASAN reports the race as: BUG: KASAN: slab-use-after-free in rds_tcp_skbuf_handler+0x2aa/0x2e0 rds_tcp_skbuf_handler net/rds/tcp.c:721 proc_sys_call_handler fs/proc/proc_sysctl.c vfs_write fs/read_write.c __x64_sys_pwrite64 fs/read_write.c Fix this by unregistering the RDS TCP sysctl table before calling rds_tcp_kill_sock(). unregister_net_sysctl_table() prevents new sysctl handlers from starting and waits for in-flight handlers to finish, so the listen socket can then be released safely. The fix was tested against the linked reproducer.
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
Other references
- git.kernel.org/stable/c/167e54c703ccd4fa028feb568b0d1002020cff86
- git.kernel.org/stable/c/16df2d154ec82e2f7e7585b4fa154751ba37729a
- git.kernel.org/stable/c/3aa13fe0c1bb7bc5312f878e61523e5d8cf3f85d
- git.kernel.org/stable/c/66fd678eef1bc2862bde5e7a0f6106256de74f30
- git.kernel.org/stable/c/80fffed08dc1c10e971066941d2daa56253f1552
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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