# CVE-2026-31596: ocfs2: handle invalid dinode in ocfs2_group_extend

> A local attacker can crash the Linux kernel by triggering a bug in the OCFS2 filesystem resize operation with a crafted filesystem image.

- **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:** 24 Apr 2026
- **Updated:** 14 Jun 2026
- **Also known as:** AZL-83684, BELL-CVE-2026-31596, DEBIAN-CVE-2026-31596, GHSA-hvjf-55rw-w8jm, ROOT-OS-DEBIAN-11-CVE-2026-31596, ROOT-OS-DEBIAN-12-CVE-2026-31596, ROOT-OS-UBUNTU-2204-CVE-2026-31596, ROOT-OS-UBUNTU-2404-CVE-2026-31596, UBUNTU-CVE-2026-31596

## What is CVE-2026-31596?

CVE-2026-31596 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Apr 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:

ocfs2: handle invalid dinode in ocfs2_group_extend

[BUG]
kernel BUG at fs/ocfs2/resize.c:308!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
RIP: 0010:ocfs2_group_extend+0x10aa/0x1ae0 fs/ocfs2/resize.c:308
Code: 8b8520ff ffff83f8 860f8580 030000e8 5cc3c1fe
Call Trace:
 ...
 ocfs2_ioctl+0x175/0x6e0 fs/ocfs2/ioctl.c:869
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x197/0x1e0 fs/ioctl.c:583
 x64_sys_call+0x1144/0x26a0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x93/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
 ...

[CAUSE]
ocfs2_group_extend() assumes that the global bitmap inode block
returned from ocfs2_inode_lock() has already been validated and
BUG_ONs when the signature is not a dinode. That assumption is too
strong for crafted filesystems because the JBD2-managed buffer path
can bypass structural validation and return an invalid dinode to the
resize ioctl.

[FIX]
Validate the dinode explicitly in ocfs2_group_extend(). If the global
bitmap buffer does not contain a valid dinode, report filesystem
corruption with ocfs2_error() and fail the resize operation instead of
crashing the kernel.

## Which versions are affected by CVE-2026-31596?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31596?

Apply the vendor's patch.

## Is CVE-2026-31596 being exploited?

There is no known exploitation of CVE-2026-31596 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-2026-31596 and fix it if it is affected.

What it is: CVE-2026-31596 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Apr 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-2026-31596 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-2026-31596/ (Markdown: https://insights.sbomify.com/CVE-2026-31596/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31596
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31596
- OSV: https://osv.dev/vulnerability/CVE-2026-31596

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31596/
Summaries are generated and may contain mistakes; the official description above is the record.