CVE-2026-98479 scsi: libiscsi_tcp: Check the data direction of a Data-In PDU
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-98479?
CVE-2026-98479 is a high-severity vulnerability in Linux, published on 18 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
scsi: libiscsi_tcp: Check the data direction of a Data-In PDU
The Data-In branch of iscsi_tcp_hdr_dissect() resolves the ITT to a task and copies the PDU's data segment into that command's scatterlist without asking whether the command was reading. iscsi_tcp_r2t_rsp() in the same file does ask, and rejects an R2T for a command that is not DMA_TO_DEVICE.
A target that answers a WRITE command's ITT with a Data-In therefore has the initiator write target-supplied bytes into the pages that write was about to send. Those are the caller's own pinned pages for an O_DIRECT write, and page cache pages for a buffered one.
Observed against a test target that emits one 512-byte Data-In naming a 128 KB write's ITT, after the R2T for that write. With O_DIRECT the caller's buffer ends up holding 512 bytes of the target's data while pwrite() returns 131072. Buffered is quieter: pwrite() and fsync() both succeed, nothing is logged, and reading those blocks back returns the target's bytes out of the page cache without a command going on the wire.
Check the direction before using the scatterlist, the way the R2T path already does.
Which versions are affected by CVE-2026-98479?
How do I fix CVE-2026-98479?
Upgrade to a fixed version.
Is CVE-2026-98479 being exploited?
There is no known exploitation of CVE-2026-98479 in the wild and no public exploit code.
Sources
Also known as AZL-109104, BELL-CVE-2026-98479, DEBIAN-CVE-2026-98479, GHSA-m9q9-jv5w-f7p7, UBUNTU-CVE-2026-98479.