# CVE-2026-98479: scsi: libiscsi_tcp: Check the data direction of a Data-In PDU


- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** AZL-109104, BELL-CVE-2026-98479, DEBIAN-CVE-2026-98479, GHSA-m9q9-jv5w-f7p7, UBUNTU-CVE-2026-98479

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98479 and fix it if it is affected.

What it is: CVE-2026-98479 is a high-severity vulnerability in Linux, published on 18 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-98479 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98479/ (Markdown: https://insights.sbomify.com/CVE-2026-98479/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98479
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98479
- OSV: https://osv.dev/vulnerability/CVE-2026-98479

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98479/
Summaries are generated and may contain mistakes; the official description above is the record.