CyberSecBulletin
CVE-2026-46135NVD status: Undergoing Analysis

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2026-46135 is a critical-severity concurrent execution using shared resource with improper synchronization 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 b7dd4d27aa70bd98bb10572310e913668baf6a65, 9c63cf80895a70eb4fcfcaa725bb1ac9ae76f02b, 6f96dea4819d122737b217ea16660d255abbf8c6 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 0.4% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to b7dd4d27aa70bd98bb10572310e913668baf6a65 or 9c63cf80895a70eb4fcfcaa725bb1ac9ae76f02b or 6f96dea4819d122737b217ea16660d255abbf8c6 or 5f0b95ef68ab9afba75b20eebf436130f80c161a, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.12.88 or 6.18.30 or 7.0.7, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, b7dd4d27aa70bd98bb10572310e913668baf6a65; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, 9c63cf80895a70eb4fcfcaa725bb1ac9ae76f02b; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, 6f96dea4819d122737b217ea16660d255abbf8c6; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, 5f0b95ef68ab9afba75b20eebf436130f80c161a; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, 49891c8fe0cb43fbbe480da1cdccfbbaeb820cb3; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, 67e1aaf93b495c2f10bc8a5fbba575fbb7f449b6; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, dcfe4d1f7960e7d1c01642318f3aae1a604f8508; 872d26a391da92ed8f0c0f5cb5fef428067b7f30 up to, but not including, 5293a8882c549fab4a878bc76b0b6c951f980a61; and 1 more rangesb7dd4d27aa70bd98bb10572310e913668baf6a65, 9c63cf80895a70eb4fcfcaa725bb1ac9ae76f02b, 6f96dea4819d122737b217ea16660d255abbf8c6, 5f0b95ef68ab9afba75b20eebf436130f80c161a, 49891c8fe0cb43fbbe480da1cdccfbbaeb820cb3, 67e1aaf93b495c2f10bc8a5fbba575fbb7f449b6
LinuxLinux Kernel5.0 up to, but not including, 6.12.88; 6.13 up to, but not including, 6.18.30; 6.19 up to, but not including, 7.0.7; 7.16.12.88, 6.18.30, 7.0.7

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: nvmet-tcp: fix race between ICReq handling and queue teardown nvmet_tcp_handle_icreq() updates queue->state after sending an Initialization Connection Response (ICResp), but it does so without serializing against target-side queue teardown. If an NVMe/TCP host sends an Initialization Connection Request (ICReq) and immediately closes the connection, target-side teardown may start in softirq context before io_work drains the already buffered ICReq. In that case, nvmet_tcp_schedule_release_queue() sets queue->state to NVMET_TCP_Q_DISCONNECTING and drops the queue reference under state_lock. If io_work later processes that ICReq, nvmet_tcp_handle_icreq() can still overwrite the state back to NVMET_TCP_Q_LIVE. That defeats the DISCONNECTING-state guard in nvmet_tcp_schedule_release_queue() and allows a later socket state change to re-enter teardown and issue a second kref_put() on an already released queue. The ICResp send failure path has the same problem. If teardown has already moved the queue to DISCONNECTING, a send error can still overwrite the state with NVMET_TCP_Q_FAILED, again reopening the window for a second teardown path to drop the queue reference. Fix this by serializing both post-send state transitions with state_lock and bailing out if teardown has already started. Use -ESHUTDOWN as an internal sentinel for that bail-out path rather than propagating it as a transport error like -ECONNRESET. Keep nvmet_tcp_socket_error() setting rcv_state to NVMET_TCP_RECV_ERR before honoring that sentinel so receive-side parsing stays quiesced until the existing release path completes.

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: yes, 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

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