CVE-2026-89721 phy: rockchip-samsung-dcphy: fix out-of-range max_register
A local attacker with debugfs access can trigger an out-of-bounds read in the Rockchip Samsung DCPHY driver, causing a kernel oops and subsequent deadlock.
- 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
What is CVE-2026-89721?
CVE-2026-89721 is a memory corruption vulnerability in Linux, published on 11 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:
phy: rockchip-samsung-dcphy: fix out-of-range max_register
The PHY register block is 64KB, so with a register stride of 4 the last accessible register sits at offset 0xfffc. max_register names 0x10000, one register past the end of the mapping: dumping the registers through the regmap debugfs interface reads beyond the ioremapped region and oopses on the unmapped page. The oops fires with the regmap lock held, so later PHY operations deadlock.
Which versions are affected by CVE-2026-89721?
How do I fix CVE-2026-89721?
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-2026-89721 being exploited?
There is no known exploitation of CVE-2026-89721 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-89721, DEBIAN-CVE-2026-89721, GHSA-jrrm-mv6f-g3m6, UBUNTU-CVE-2026-89721.