Detections
Analytics
Linux Distros Unpatched Vulnerability : CVE-2026-31584
medium Nessus Plugin ID 310308
Synopsis
The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.Description
The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.- media: mediatek: vcodec: fix use-after-free in encoder release path The fops_vcodec_release() function frees the context structure (ctx) without first cancelling any pending or running work in ctx->encode_work. This creates a race window where the workqueue handler (mtk_venc_worker) may still be accessing the context memory after it has been freed. Race condition: CPU 0 (release path) CPU 1 (workqueue) --------------------- ------------------ fops_vcodec_release() v4l2_m2m_ctx_release() v4l2_m2m_cancel_job() // waits for m2m job done mtk_venc_worker() v4l2_m2m_job_finish() // m2m job done // BUT worker still running! // post-job_finish access: other ctx dereferences // UAF if ctx already freed // returns (job done) kfree(ctx) // ctx freed Root cause: The v4l2_m2m_ctx_release() only waits for the m2m job lifecycle (via TRANS_RUNNING flag), not the workqueue lifecycle. After v4l2_m2m_job_finish() is called, the m2m framework considers the job complete and v4l2_m2m_ctx_release() returns, but the worker function continues executing and may still access ctx. The work is queued during encode operations via: queue_work(ctx->dev->encode_workqueue, &ctx->encode_work) The worker function accesses ctx->m2m_ctx, ctx->dev, and other ctx fields even after calling v4l2_m2m_job_finish(). This vulnerability was confirmed with KASAN by running an instrumented test module that widens the post- job_finish race window. KASAN detected: BUG: KASAN: slab-use-after-free in mtk_venc_worker+0x159/0x180 Read of size 4 at addr ffff88800326e000 by task kworker/u8:0/12 Workqueue: mtk_vcodec_enc_wq mtk_venc_worker Allocated by task 47: __kasan_kmalloc+0x7f/0x90 fops_vcodec_open+0x85/0x1a0 Freed by task 47: __kasan_slab_free+0x43/0x70 kfree+0xee/0x3a0 fops_vcodec_release+0xb7/0x190 Fix this by calling cancel_work_sync(&ctx->encode_work) before kfree(ctx). This ensures the workqueue handler is both cancelled (if pending) and synchronized (waits for any running handler to complete) before the context is freed. Placement rationale: The fix is placed after v4l2_ctrl_handler_free() and before list_del_init(&ctx->list). At this point, all m2m operations are done (v4l2_m2m_ctx_release() has returned), and we need to ensure the workqueue is synchronized before removing ctx from the list and freeing it. Note: The open error path does NOT need cancel_work_sync() because INIT_WORK() only initializes the work structure - it does not schedule it. Work is only scheduled later during device_run() operations. (CVE-2026-31584)
Note that Nessus relies on the presence of the package as reported by the vendor.
Solution
There is no known solution at this time.See Also
Plugin Details
Severity: Medium
ID: 310308
File Name: unpatched_CVE_2026_31584.nasl
Version: 1.1
Type: Local
Agent: unix
Family: Misc.
Published: 4/25/2026
Updated: 4/25/2026
Supported Sensors: Nessus Agent, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 6.0
CVSS v2
Risk Factor: Medium
Base Score: 6.3
Temporal Score: 5.4
Vector: CVSS2#AV:L/AC:M/Au:N/C:C/I:N/A:C
CVSS Score Source: CVE-2026-31584
CVSS v3
Risk Factor: Medium
Base Score: 6.3
Temporal Score: 5.8
Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:U/RC:C
Vulnerability Information
CPE: cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:linux, cpe:/o:debian:debian_linux:14.0, cpe:/o:debian:debian_linux:12.0, cpe:/o:debian:debian_linux:13.0
Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier
Exploit Ease: No known exploits are available
Vulnerability Publication Date: 4/24/2026
Reference Information
CVE: CVE-2026-31584