CVE-2026-98027 net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size
A local user can cause a kernel crash or memory corruption in the Marvell DSA driver by triggering a buffer overflow during policy rule dumps.
- 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-2026-98027?
CVE-2026-98027 is a high-severity denial of service vulnerability in Linux, published on 25 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:
net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size
mv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while dumping the policy IDR, clobbering the input value before it has been looked at. That input is the number of entries the caller had room for. ETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the buffer from the rule_cnt userspace passes in, so once an admin has installed policy rules any user can ask for fewer slots than there are rules and run off the end of the allocation. A rule_cnt of 0 leaves the buffer pointer NULL and the walk dereferences it.
Count into a local so the caller's limit survives the walk, and stop with -EMSGSIZE once it is reached.
Which versions are affected by CVE-2026-98027?
How do I fix CVE-2026-98027?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-98027 being exploited?
There is no known exploitation of CVE-2026-98027 in the wild and no public exploit code.
Sources
Also known as AZL-104448, BELL-CVE-2026-98027, DEBIAN-CVE-2026-98027, GHSA-rmvm-8mw4-j874, UBUNTU-CVE-2026-98027.