CVE-2026-90191 mailbox: riscv-sbi-mpxy: validate RPMI notification lengths
A missing length validation in the Linux kernel RISC-V SBI mailbox driver allows memory corruption via crafted RPMI notifications, potentially leading to code execution or crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90191?
CVE-2026-90191 is a high-severity memory corruption vulnerability in Linux, published on 17 Sep 2026. 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:
mailbox: riscv-sbi-mpxy: validate RPMI notification lengths
The SBI return value controls how many bytes are copied from shared memory into the RPMI notification buffer. It is not validated against the negotiated shared-memory size before that copy. The event walker also uses a reversed loop condition and can inspect a short event record.
Validate the complete notification length before copying it, iterate only while a full event header remains, and stop when a declared event payload extends beyond the copied notification data.
Which versions are affected by CVE-2026-90191?
How do I fix CVE-2026-90191?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-90191 being exploited?
There is no known exploitation of CVE-2026-90191 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-90191, DEBIAN-CVE-2026-90191, GHSA-m5w6-3p2w-2mgg, UBUNTU-CVE-2026-90191.