# CVE-2021-47027: mt76: mt7921: fix kernel crash when the firmware fails to download > A missing firmware download in the mt7921 driver causes a kernel crash, leading to a denial of service. - **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 28 Feb 2024 - **Updated:** 11 May 2026 - **Also known as:** GHSA-m8jx-hpg8-g7ww, UBUNTU-CVE-2021-47027 ## What is CVE-2021-47027? CVE-2021-47027 is a medium-severity vulnerability in Linux kernel, published on 28 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: mt76: mt7921: fix kernel crash when the firmware fails to download Fix kernel crash when the firmware is missing or fails to download. [ 9.444758] kernel BUG at drivers/pci/msi.c:375! [ 9.449363] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [ 9.501033] pstate: a0400009 (NzCv daif +PAN -UAO) [ 9.505814] pc : free_msi_irqs+0x180/0x184 [ 9.509897] lr : free_msi_irqs+0x40/0x184 [ 9.513893] sp : ffffffc015193870 [ 9.517194] x29: ffffffc015193870 x28: 00000000f0e94fa2 [ 9.522492] x27: 0000000000000acd x26: 000000000000009a [ 9.527790] x25: ffffffc0152cee58 x24: ffffffdbb383e0d8 [ 9.533087] x23: ffffffdbb38628d0 x22: 0000000000040200 [ 9.538384] x21: ffffff8cf7de7318 x20: ffffff8cd65a2480 [ 9.543681] x19: ffffff8cf7de7000 x18: 0000000000000000 [ 9.548979] x17: ffffff8cf9ca03b4 x16: ffffffdc13ad9a34 [ 9.554277] x15: 0000000000000000 x14: 0000000000080800 [ 9.559575] x13: ffffff8cd65a2980 x12: 0000000000000000 [ 9.564873] x11: ffffff8cfa45d820 x10: ffffff8cfa45d6d0 [ 9.570171] x9 : 0000000000000040 x8 : ffffff8ccef1b780 [ 9.575469] x7 : aaaaaaaaaaaaaaaa x6 : 0000000000000000 [ 9.580766] x5 : ffffffdc13824900 x4 : ffffff8ccefe0000 [ 9.586063] x3 : 0000000000000000 x2 : 0000000000000000 [ 9.591362] x1 : 0000000000000125 x0 : ffffff8ccefe0000 [ 9.596660] Call trace: [ 9.599095] free_msi_irqs+0x180/0x184 [ 9.602831] pci_disable_msi+0x100/0x130 [ 9.606740] pci_free_irq_vectors+0x24/0x30 [ 9.610915] mt7921_pci_probe+0xbc/0x250 [mt7921e] [ 9.615693] pci_device_probe+0xd4/0x14c [ 9.619604] really_probe+0x134/0x2ec [ 9.623252] driver_probe_device+0x64/0xfc [ 9.627335] device_driver_attach+0x4c/0x6c [ 9.631506] __driver_attach+0xac/0xc0 [ 9.635243] bus_for_each_dev+0x8c/0xd4 [ 9.639066] driver_attach+0x2c/0x38 [ 9.642628] bus_add_driver+0xfc/0x1d0 [ 9.646365] driver_register+0x64/0xf8 [ 9.650101] __pci_register_driver+0x6c/0x7c [ 9.654360] init_module+0x28/0xfdc [mt7921e] [ 9.658704] do_one_initcall+0x13c/0x2d0 [ 9.662615] do_init_module+0x58/0x1e8 [ 9.666351] load_module+0xd80/0xeb4 [ 9.669912] __arm64_sys_finit_module+0xa8/0xe0 [ 9.674430] el0_svc_common+0xa4/0x16c [ 9.678168] el0_svc_compat_handler+0x2c/0x40 [ 9.682511] el0_svc_compat+0x8/0x10 [ 9.686076] Code: a94257f6 f9400bf7 a8c47bfd d65f03c0 (d4210000) [ 9.692155] ---[ end trace 7621f966afbf0a29 ]--- [ 9.697385] Kernel panic - not syncing: Fatal exception [ 9.702599] SMP: stopping secondary CPUs [ 9.706549] Kernel Offset: 0x1c03600000 from 0xffffffc010000000 [ 9.712456] PHYS_OFFSET: 0xfffffff440000000 [ 9.716625] CPU features: 0x080026,2a80aa18 [ 9.720795] Memory Limit: none ## Which versions are affected by CVE-2021-47027? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2021-47027? No fix has been published for CVE-2021-47027 yet. Limit exposure of the affected software until one is available. ## Is CVE-2021-47027 being exploited? There is no known exploitation of CVE-2021-47027 in the wild and no public exploit code. ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-47027 and fix it if it is affected. What it is: CVE-2021-47027 is a medium-severity vulnerability in Linux kernel, published on 28 Feb 2024. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-47027 in the wild and no public exploit code. Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-47027/ (Markdown: https://insights.sbomify.com/CVE-2021-47027/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47027 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47027 - OSV: https://osv.dev/vulnerability/CVE-2021-47027 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-47027/ Summaries are generated and may contain mistakes; the official description above is the record.