Linux: Use After Free
CVE-2026-68397 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 5739be5c19495d709d902a2912c9102ce78740d5, bc6c6e546ffff8865daaeb622ef348c2d481e80f, e3e0679fc950191aff8f27fa78abcfc2462cff4a 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 0.26% 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 5739be5c19495d709d902a2912c9102ce78740d5 or bc6c6e546ffff8865daaeb622ef348c2d481e80f or e3e0679fc950191aff8f27fa78abcfc2462cff4a or 4dc0e63abf8bc7ba8892e617c1fb8b204361e022, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 3881ac441f642d56503818123446f7298442236b up to, but not including, 5739be5c19495d709d902a2912c9102ce78740d5; 3881ac441f642d56503818123446f7298442236b up to, but not including, bc6c6e546ffff8865daaeb622ef348c2d481e80f; 3881ac441f642d56503818123446f7298442236b up to, but not including, e3e0679fc950191aff8f27fa78abcfc2462cff4a; 3881ac441f642d56503818123446f7298442236b up to, but not including, 4dc0e63abf8bc7ba8892e617c1fb8b204361e022; 3881ac441f642d56503818123446f7298442236b up to, but not including, 1801cb20a5025a787d6853e19c38db138344b4b4; 3881ac441f642d56503818123446f7298442236b up to, but not including, c75a950e77356e526672cba4584080c6c8b793b6; 3881ac441f642d56503818123446f7298442236b up to, but not including, 5595ea59cdf29182cf6a270cacc1426c57b603de; 3881ac441f642d56503818123446f7298442236b up to, but not including, 4fa349156043dc119721d067329714179f501749; and 1 more ranges | 5739be5c19495d709d902a2912c9102ce78740d5, bc6c6e546ffff8865daaeb622ef348c2d481e80f, e3e0679fc950191aff8f27fa78abcfc2462cff4a, 4dc0e63abf8bc7ba8892e617c1fb8b204361e022, 1801cb20a5025a787d6853e19c38db138344b4b4, c75a950e77356e526672cba4584080c6c8b793b6 |
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
- AdjacentThe attacker must be on the same local network segment.
- 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:A/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: net/iucv: take a reference on the socket found in afiucv_hs_rcv() afiucv_hs_rcv() looks up the destination socket under iucv_sk_list.lock, drops the lock, and then passes the socket to the afiucv_hs_callback_*() handlers without holding a reference. AF_IUCV sockets are not RCU-protected and are freed synchronously by iucv_sock_kill() -> sock_put(), so a concurrent close can free the socket in the window between read_unlock() and the handler, which then dereferences freed memory (for example sk->sk_data_ready() in afiucv_hs_callback_syn()). Take a reference with sock_hold() while the socket is still on the list and release it with sock_put() once the handler has run.
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/1801cb20a5025a787d6853e19c38db138344b4b4
- git.kernel.org/stable/c/4dc0e63abf8bc7ba8892e617c1fb8b204361e022
- git.kernel.org/stable/c/4fa349156043dc119721d067329714179f501749
- git.kernel.org/stable/c/5595ea59cdf29182cf6a270cacc1426c57b603de
- git.kernel.org/stable/c/5739be5c19495d709d902a2912c9102ce78740d5
- git.kernel.org/stable/c/bc6c6e546ffff8865daaeb622ef348c2d481e80f
- git.kernel.org/stable/c/c75a950e77356e526672cba4584080c6c8b793b6
- git.kernel.org/stable/c/e3e0679fc950191aff8f27fa78abcfc2462cff4a
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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