# CVE-2026-80688: riscv: drop __init from vec_check_unaligned_access_speed_all_cpus

> A kernel bug causes a use-after-free condition in RISC-V vector initialization, leading to a system crash if the boot process is delayed.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-80688, DEBIAN-CVE-2026-80688, GHSA-89m2-3f67-ff57, UBUNTU-CVE-2026-80688

## What is CVE-2026-80688?

CVE-2026-80688 is an use after free vulnerability in Linux, published on 28 Aug 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

riscv: drop __init from vec_check_unaligned_access_speed_all_cpus

This function runs within a kthread and need not necessarily finish
before system finishes boot and free_initmem() unmaps the .init.text
section. This function makes calls to SBI for probing unaligned access
speed, and if this is slow for some reason (say some debug prints were
added to SBI), the kthread can still be running at this point and result
in an instruction page fault when trying to fetch from the freed region.

[   25.642087] Unable to handle kernel paging request at virtual address ffffffff80a04ef8
[   25.646694] Current vec_check_unali pgtable: 4K pagesize, 48-bit VAs, pgdp=0x00004000316e9000
[   25.653170] [ffffffff80a04ef8] pgd=000010004be7e401, p4d=000010004be7e401, pud=000010004be7e001, pmd=000010000c3000e3
[   25.661244] Oops [#1]
[   25.662997] Modules linked in:
[   25.665357] CPU: 3 UID: 0 PID: 42 Comm: vec_check_unali Not tainted 7.0.0-tt-blackhole-asrinivasan-00007-g30ff73f18211 #570 PREEMPTLAZY
[   25.674669] Hardware name: Tenstorrent Blackhole (DT)
[   25.678545] epc : vec_check_unaligned_access_speed_all_cpus+0x18/0x2c
[   25.683458]  ra : vec_check_unaligned_access_speed_all_cpus+0x18/0x2c
[   25.688372] epc : ffffffff80a04ef8 ra : ffffffff80a04ef8 sp : ffff8f8000203e20
[   25.693874]  gp : ffffffff814dc168 tp : ffffaf8001ad9900 t0 : 0000000000000000
[   25.699401]  t1 : fffffffffffffff0 t2 : ffffaf8001ad9a10 s0 : ffff8f8000203e30
[   25.704912]  s1 : ffffaf80018dc780 a0 : 0000000000000000 a1 : 0000000000000002
[   25.710407]  a2 : 00000000000001f0 a3 : 0000000000000018 a4 : 0000000000000000
[   25.715917]  a5 : 0000000000000000 a6 : ffffaf8001c03d98 a7 : ffffaf8001c03e30
[   25.721419]  s2 : ffff8f8000023c98 s3 : ffffaf8001aa1240 s4 : ffffffff80a04ee0
[   25.726937]  s5 : 0000000000000000 s6 : 0000000000000000 s7 : 0000000000000000
[   25.732450]  s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000
[   25.737944]  s11: 0000000000000000 t3 : 0000000000000002 t4 : 0000000000000402
[   25.743481]  t5 : 0000000000000040 t6 : 0000000000000004 ssp : 0000000000000000
[   25.749024] status: 0000000200000120 badaddr: ffffffff80a04ef8 cause: 000000000000000c
[   25.755060] [<ffffffff80a04ef8>] vec_check_unaligned_access_speed_all_cpus+0x18/0x2c
[   25.760964] [<ffffffff80047a10>] kthread+0xd8/0xfc
[   25.764660] [<ffffffff80010c48>] ret_from_fork_kernel+0x18/0x1c4
[   25.769220] [<ffffffff80895fe6>] ret_from_fork_kernel_asm+0x16/0x18
[   25.774018] Code: cccc cccc cccc cccc cccc cccc cccc cccc cccc cccc (cccc) cccc

Drop __init from its signature so that this doesn't happen.

## Which versions are affected by CVE-2026-80688?


## How do I fix CVE-2026-80688?

Apply the vendor's patch.

## Is CVE-2026-80688 being exploited?

There is no known exploitation of CVE-2026-80688 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80688 and fix it if it is affected.

What it is: CVE-2026-80688 is an use after free vulnerability in Linux, published on 28 Aug 2026. 
Exploitation: There is no known exploitation of CVE-2026-80688 in the wild and no public exploit code.

Affected product: Linux. 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-2026-80688/ (Markdown: https://insights.sbomify.com/CVE-2026-80688/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80688
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80688
- OSV: https://osv.dev/vulnerability/CVE-2026-80688

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80688/
Summaries are generated and may contain mistakes; the official description above is the record.