CyberSecBulletin
CVE-2026-68323NVD status: Received

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2026-68323 is a high-severity concurrent execution using shared resource with improper synchronization 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 c148aec60ef1e806cbc9da44b3d89409df998ade, 3ff6b534d20824cddab99c81ea3bd1144e635626, 3ff143a884a19bfcf3aebd999b02274fe44f46f3 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 0.1% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to c148aec60ef1e806cbc9da44b3d89409df998ade or 3ff6b534d20824cddab99c81ea3bd1144e635626 or 3ff143a884a19bfcf3aebd999b02274fe44f46f3 or 5d3cea7d41dc72073fea6f879815c9b57c3b330d, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxef20cd4dd1633987bcf46ac34ace2c8af212361f up to, but not including, c148aec60ef1e806cbc9da44b3d89409df998ade; ef20cd4dd1633987bcf46ac34ace2c8af212361f up to, but not including, 3ff6b534d20824cddab99c81ea3bd1144e635626; ef20cd4dd1633987bcf46ac34ace2c8af212361f up to, but not including, 3ff143a884a19bfcf3aebd999b02274fe44f46f3; ef20cd4dd1633987bcf46ac34ace2c8af212361f up to, but not including, 5d3cea7d41dc72073fea6f879815c9b57c3b330d; ef20cd4dd1633987bcf46ac34ace2c8af212361f up to, but not including, d70c81001df9320d3445e664428a1d408b5ba896; ef20cd4dd1633987bcf46ac34ace2c8af212361f up to, but not including, 350e592ff4e30e48ffb55e142d11a73e63f4869c; 4.9c148aec60ef1e806cbc9da44b3d89409df998ade, 3ff6b534d20824cddab99c81ea3bd1144e635626, 3ff143a884a19bfcf3aebd999b02274fe44f46f3, 5d3cea7d41dc72073fea6f879815c9b57c3b330d, d70c81001df9320d3445e664428a1d408b5ba896, 350e592ff4e30e48ffb55e142d11a73e63f4869c

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: tipc: serialize udp bearer replicast list updates tipc_udp_rcast_add() and cleanup_bearer() both update ub->rcast.list with list_add_rcu() / list_del_rcu(), but nothing serializes them. The add runs from the encap receive softirq (via tipc_udp_rcast_disc()) without rtnl_lock(), so it can race the cleanup delete and corrupt the list: list_del corruption. prev->next should be ffff8880298d7ab8, but was ffff88802449ad38. (prev=ffff888027e3ec98) kernel BUG at lib/list_debug.c:62! RIP: __list_del_entry_valid_or_report+0x17a/0x200 Workqueue: events cleanup_bearer Call Trace: cleanup_bearer (net/tipc/udp_media.c:811) process_one_work (kernel/workqueue.c:3302) worker_thread (kernel/workqueue.c:3466) The bearer can be enabled from an unprivileged user namespace, as the TIPCv2 generic-netlink ops carry no GENL_ADMIN_PERM. Add a spinlock to struct udp_bearer and take it around the list_add_rcu() in tipc_udp_rcast_add() and the list_del_rcu() loop in cleanup_bearer() so the two writers can no longer corrupt the list. Reject a duplicate peer under the same lock before allocating, and remove tipc_udp_is_known_peer(). The old lockless pre-check in tipc_udp_rcast_disc() was racy: two softirqs discovering the same peer could both find it absent and add it twice. cleanup_bearer() runs from a workqueue after tipc_udp_disable() clears the bearer's up bit, so an encap softirq can still reach tipc_udp_rcast_add() and add a peer after cleanup_bearer() has already emptied the list, leaking that entry when the bearer is freed. Mark the bearer disabled under rcast_lock once the list is emptied and refuse further additions.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How developers prevent this class of flaw

  • In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
  • Use thread-safe capabilities such as the data access abstraction in Spring.
  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

More Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities (CWE-362)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities

Spotted an error? Tell us.