Linux: Use After Free
CVE-2026-68201 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 cd461bcfcdf8d6b6b5365941c1d3859f8bc77aa0, 426c0ff1c433d6030610ad4f9375746dfe931caa, 2b298997786876b225cff2446e11a0fa6f602f6d 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 0.17% 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 cd461bcfcdf8d6b6b5365941c1d3859f8bc77aa0 or 426c0ff1c433d6030610ad4f9375746dfe931caa or 2b298997786876b225cff2446e11a0fa6f602f6d or bdefe1346a8e6b8dc8593406dc2617e985fcbcab, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 37745918e0e7575bc40f38da93a99b9fa6406224 up to, but not including, cd461bcfcdf8d6b6b5365941c1d3859f8bc77aa0; 37745918e0e7575bc40f38da93a99b9fa6406224 up to, but not including, 426c0ff1c433d6030610ad4f9375746dfe931caa; 37745918e0e7575bc40f38da93a99b9fa6406224 up to, but not including, 2b298997786876b225cff2446e11a0fa6f602f6d; 37745918e0e7575bc40f38da93a99b9fa6406224 up to, but not including, bdefe1346a8e6b8dc8593406dc2617e985fcbcab; 6.12 | cd461bcfcdf8d6b6b5365941c1d3859f8bc77aa0, 426c0ff1c433d6030610ad4f9375746dfe931caa, 2b298997786876b225cff2446e11a0fa6f602f6d, bdefe1346a8e6b8dc8593406dc2617e985fcbcab |
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: ALSA: timer: drain a slave's callback before its master detaches it snd_timer_close_locked() drains the closing instance's own in-flight callback (IFLG_CALLBACK) before freeing it, but not its slaves'. When a master instance is closed, remove_slave_links() clears each slave's ->timer; the slave's own close then reads timer == NULL and takes the branch that skips the drain entirely (snd_timer_stop_slave() also no-ops on a NULL timer). So a slave whose callback is still running when the master is closed is freed underneath the live callback, leading to use-after-free. Drain the slaves too before remove_slave_links() severs them. snd_timer_stop() has already taken this instance off the active list, so no new slave callback can be queued. Take the slaves off the ack list so a pending one can't fire either, then wait for any that is already in flight.
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
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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