# CVE-2026-72482: gpib: fix double decrement of descriptor_busy in command_ioctl()

> A double decrement of a reference counter in the Linux kernel gpib driver allows a use-after-free, potentially enabling code execution or privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72482, DEBIAN-CVE-2026-72482, GHSA-g7v6-7vr9-25jq, UBUNTU-CVE-2026-72482

## What is CVE-2026-72482?

CVE-2026-72482 is a high-severity use after free vulnerability in Linux, published on 15 Aug 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:

gpib: fix double decrement of descriptor_busy in command_ioctl()

commit d1857f8296dc ("gpib: fix use-after-free in IO ioctl handlers")
introduced a descriptor_busy reference counter to pin struct
gpib_descriptor across IO ioctl operations.  In command_ioctl(), the
error path inside the loop decrements descriptor_busy and breaks, but
execution then falls through to the unconditional decrement after the
loop, underflowing the counter to -1.

This re-enables the use-after-free that the original fix was meant to
prevent: a concurrent close_dev_ioctl() sees descriptor_busy == 0 on
an actively-used descriptor and frees it.

Remove the early decrement from the error path.  The post-loop
decrement already handles all exit paths, matching the correct pattern
used in read_ioctl() and write_ioctl().

## Which versions are affected by CVE-2026-72482?


## How do I fix CVE-2026-72482?

Apply the vendor's patch.

## Is CVE-2026-72482 being exploited?

There is no known exploitation of CVE-2026-72482 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72482 and fix it if it is affected.

What it is: CVE-2026-72482 is a high-severity use after free vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72482 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-2026-72482/ (Markdown: https://insights.sbomify.com/CVE-2026-72482/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72482
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72482
- OSV: https://osv.dev/vulnerability/CVE-2026-72482

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72482/
Summaries are generated and may contain mistakes; the official description above is the record.