CVE-2026-89481 nvme-tcp: fix host memory disclosure on R2T for a read command
A malicious NVMe controller can trigger host memory disclosure by sending an R2T for a read command, leaking stale kernel data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89481?
CVE-2026-89481 is a high-severity vulnerability in Linux, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
nvme-tcp: fix host memory disclosure on R2T for a read command
nvme_tcp_handle_r2t() does not check the direction of the request the R2T refers to. A malicious controller can send an R2T for a READ and the host will answer it: nvme_tcp_setup_h2c_data_pdu() builds the H2CData header and nvme_tcp_try_send_data() sends the request's data buffer. That buffer is the READ destination, so its contents go to the controller.
The command then completes normally and nothing is logged.
Against a test controller that answers every READ with an R2T, a 4096 byte buffered read returned all 4096 bytes, split over two R2Ts. The pages contained stale kernel data, including an array of struct page pointers.
Reject an R2T for a request that is not a write.
Which versions are affected by CVE-2026-89481?
How do I fix CVE-2026-89481?
Apply the vendor's patch.
Is CVE-2026-89481 being exploited?
There is no known exploitation of CVE-2026-89481 in the wild and no public exploit code.
Sources
Also known as AZL-100646, BELL-CVE-2026-89481, DEBIAN-CVE-2026-89481, GHSA-fmg2-x8fr-fw62, UBUNTU-CVE-2026-89481.