# CVE-2026-72083: scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE

> A use-after-free vulnerability in the Linux kernel's iSCSI target allows attackers to cause denial of service or potentially execute code via crafted SCSI commands.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-72083, DEBIAN-CVE-2026-72083, GHSA-4wvq-w7j8-wrfm, UBUNTU-CVE-2026-72083

## What is CVE-2026-72083?

CVE-2026-72083 is a critical use after free vulnerability in Linux, published on 15 Aug 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:

scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE

core_scsi3_emulate_pro_register_and_move() maps the PERSISTENT RESERVE OUT
parameter list with transport_kmap_data_sg() and parses the destination
TransportID with target_parse_pr_out_transport_id(). For an iSCSI
TransportID (FORMAT CODE 01b), iscsi_parse_pr_out_transport_id() returns
the ISID in iport_ptr as a raw pointer into that mapped buffer.

The function then unmaps the buffer with transport_kunmap_data_sg() before
dereferencing iport_ptr in strcmp(), __core_scsi3_locate_pr_reg() and
core_scsi3_alloc_registration(). When the parameter list spans more than
one page (PARAMETER LIST LENGTH > 4096), transport_kmap_data_sg() uses
vmap() and transport_kunmap_data_sg() does vunmap(), so the kernel virtual
address backing iport_ptr is torn down and every subsequent dereference is
a use-after-free read of the unmapped region.

Keep the parameter list mapped until iport_ptr is no longer needed: drop
the early transport_kunmap_data_sg() and unmap once on the success path,
right before returning. The error paths already unmap through the existing
"if (buf) transport_kunmap_data_sg(cmd)" at the out: label, which now runs
on every post-map error exit because buf is no longer cleared early. Only
reads of the mapping happen while spinlocks are held; the map and unmap
calls remain outside any lock. The sibling caller
core_scsi3_decode_spec_i_port() already uses the buffer before unmapping it
and is left unchanged.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-72083?


## How do I fix CVE-2026-72083?

Apply the vendor's patch.

## Is CVE-2026-72083 being exploited?

There is no known exploitation of CVE-2026-72083 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72083 and fix it if it is affected.

What it is: CVE-2026-72083 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72083 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-2026-72083/ (Markdown: https://insights.sbomify.com/CVE-2026-72083/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72083
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72083
- OSV: https://osv.dev/vulnerability/CVE-2026-72083

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72083/
Summaries are generated and may contain mistakes; the official description above is the record.