CyberSecBulletin
CVE-2026-64438NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-64438 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 with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 218c2836b3987f3fa1d9eac505462cded0821e4c, 446b4d77599cf1a168573f7fb32a4a6aa4f09219, 5d916c1eae1933511a69bffe243b4ee5d7da399c 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 0.14% 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 218c2836b3987f3fa1d9eac505462cded0821e4c or 446b4d77599cf1a168573f7fb32a4a6aa4f09219 or 5d916c1eae1933511a69bffe243b4ee5d7da399c or f344a369d0380d54c8d6c8d24734a78dd5a89817, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, 218c2836b3987f3fa1d9eac505462cded0821e4c; ed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, 446b4d77599cf1a168573f7fb32a4a6aa4f09219; ed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, 5d916c1eae1933511a69bffe243b4ee5d7da399c; ed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, f344a369d0380d54c8d6c8d24734a78dd5a89817; ed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, 51144032248cc4ea22917370565650670b8b4e9b; ed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, 49cd5ac6de8de39a14ead609bb552d372d5602cd; ed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, 6e92b28cd74fa433658efeadf21b9d4b01023d7d; ed8ccaef52fa03fb03cff45b380f72c9f869f273 up to, but not including, 277281c10c63791067d24d421f7c43a15faa9096; and 1 more ranges218c2836b3987f3fa1d9eac505462cded0821e4c, 446b4d77599cf1a168573f7fb32a4a6aa4f09219, 5d916c1eae1933511a69bffe243b4ee5d7da399c, f344a369d0380d54c8d6c8d24734a78dd5a89817, 51144032248cc4ea22917370565650670b8b4e9b, 49cd5ac6de8de39a14ead609bb552d372d5602cd
LinuxLinux Kernel4.3 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.97; 6.13 up to, but not including, 6.18.40; 6.19 up to, but not including, 7.1.45.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40

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
ChangedThe attack can reach beyond the vulnerable component into other systems.
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:C/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: crypto: qat - fix VF2PF work teardown race in adf_disable_sriov() The VF2PF interrupt handler queues PF-side response work that stores a raw pointer to per-VF state (struct adf_accel_vf_info). Currently, adf_disable_sriov() destroys per-VF mutexes and frees vf_info without stopping new VF2PF work or waiting for in-flight workers to complete. A concurrently scheduled or already queued worker can then dereference freed memory. This manifests as a use-after-free when KASAN is enabled: BUG: KASAN: null-ptr-deref in mutex_lock+0x76/0xe0 Write of size 8 at addr 0000000000000260 by task kworker/24:2/... Workqueue: qat_pf2vf_resp_wq adf_iov_send_resp [intel_qat] Call Trace: kasan_report+0x119/0x140 mutex_lock+0x76/0xe0 adf_gen4_pfvf_send+0xd4/0x1f0 [intel_qat] adf_recv_and_handle_vf2pf_msg+0x290/0x360 [intel_qat] adf_iov_send_resp+0x8c/0xe0 [intel_qat] process_one_work+0x6ac/0xfd0 worker_thread+0x4dd/0xd30 kthread+0x326/0x410 ret_from_fork+0x33b/0x670 Add a PF-local flag, vf2pf_disabled, that gates work queueing, worker processing, and interrupt re-enabling during teardown. Set this flag atomically with the hardware interrupt mask inside adf_disable_all_vf2pf_interrupts(). After masking, synchronize the AE cluster MSI-X interrupt and flush the PF response workqueue before tearing down per-VF locks and state so all in-flight work completes before vf_info is destroyed. Introduce adf_enable_all_vf2pf_interrupts() to clear the flag and unmask all VF2PF interrupts under the same lock when SR-IOV is re-enabled. This ensures the software flag and hardware state transition atomically on both the enable and disable paths.

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.

More Use After Free vulnerabilities (CWE-416)

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 Use After Free vulnerabilities

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