# CVE-2026-53304: scsi: sg: Resolve soft lockup issue when opening /dev/sgX

> A local attacker with root privileges can cause a kernel soft lockup by setting an invalid module parameter, leading to system unavailability.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 26 Jun 2026
- **Updated:** 26 Jun 2026
- **Also known as:** BELL-CVE-2026-53304, DEBIAN-CVE-2026-53304, GHSA-cx67-j66h-cm23, ROOT-OS-UBUNTU-2204-CVE-2026-53304, ROOT-OS-UBUNTU-2404-CVE-2026-53304, UBUNTU-CVE-2026-53304

## What is CVE-2026-53304?

CVE-2026-53304 is a medium-severity denial of service vulnerability in Linux kernel, published on 26 Jun 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:

scsi: sg: Resolve soft lockup issue when opening /dev/sgX

The parameter def_reserved_size defines the default buffer size reserved
for each Sg_fd and should be restricted to a range between 0 and 1,048,576
(see https://tldp.org/HOWTO/SCSI-Generic-HOWTO/proc.html).  Although the
function sg_proc_write_dressz enforces this limit, it is possible to bypass
it by directly modifying the module parameter as shown below, which then
causes a soft lockup:

echo -1 > /sys/module/sg/parameters/def_reserved_size
exec 4<> /dev/sg0

watchdog: BUG: soft lockup - CPU#5 stuck for 26 seconds! [bash:537]
Modules loaded:
CPU: 5 UID: 0 PID: 537 Command: bash, kernel version 6.19.0-rc3+ #134,
PREEMPT disabled
Hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS version
1.16.1-2.fc37 dated 04/01/2014
...
Call Trace:

  sg_build_reserve+0x5c/0xa0
  sg_add_sfp+0x168/0x270
  sg_open+0x16e/0x340
  chrdev_open+0xbe/0x230
  do_dentry_open+0x175/0x480
  vfs_open+0x34/0xf0
  do_open+0x265/0x3d0
  path_openat+0x110/0x290
  do_filp_open+0xc3/0x170
  do_sys_openat2+0x71/0xe0
  __x64_sys_openat+0x6d/0xa0
  do_syscall_64+0x62/0x310
  entry_SYSCALL_64_after_hwframe+0x76/0x7e

The fix is to use module_param_cb to validate and reject invalid values
assigned to def_reserved_size.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-53304?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53304?

Apply the vendor's patch.

## Is CVE-2026-53304 being exploited?

There is no known exploitation of CVE-2026-53304 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53304 and fix it if it is affected.

What it is: CVE-2026-53304 is a medium-severity denial of service vulnerability in Linux kernel, published on 26 Jun 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-2026-53304 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-53304/ (Markdown: https://insights.sbomify.com/CVE-2026-53304/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53304
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53304
- OSV: https://osv.dev/vulnerability/CVE-2026-53304

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53304/
Summaries are generated and may contain mistakes; the official description above is the record.