# CVE-2026-31584: media: mediatek: vcodec: fix use-after-free in encoder release path CVE-2026-31584 is fixed in 14 products on 1 platform, first by DEBIAN-CVE-2026-31584, released May 15, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-31584 - Priority: High - CVSS: 7.8 (Important) - EPSS: 0.0013 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Apr 24, 2026 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31584 ## Description In the Linux kernel, the following vulnerability has been resolved: 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. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | dtb-aarch64 opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-64kb opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-64kb sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-azure opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-azure sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-default opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-default sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-default-base opensuse-leap 16.0 | 6.12.0-160000.35.1.160000.2.16 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-default-base sles 16.0 | 6.12.0-160000.35.1.160000.2.16 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-docs opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-docs sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-kvmsmall opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-kvmsmall sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-obs-build opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-obs-qa opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-obs-qa sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-rt opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-source opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-source sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-syms opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-syms sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | kernel-zfcpdump opensuse-leap 16.0 | 6.12.0-160000.35.1 | [OPENSUSE-SU-2026:20965-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20965-1.md) | Jun 15, 2026 | | Linux | kernel-zfcpdump sles 16.0 | 6.12.0-160000.35.1 | [SUSE-SU-2026:22127-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22127-1.md) | Jun 15, 2026 | | Linux | linux Debian 13.5 (trixie) | 6.12.85-1 | [DEBIAN-CVE-2026-31584](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31584.md) | May 15, 2026 | | Linux | linux Debian 14 | 6.19.14-1 | [DEBIAN-CVE-2026-31584](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31584.md) | May 15, 2026 | --- Data as of 2026-11-09T01:18:40Z UTC. 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