# CVE-2026-53039: ocfs2: validate group add input before caching

> A local attacker can trigger a kernel BUG_ON crash in the OCFS2 filesystem by passing invalid input to the group add ioctl, causing a denial of service.

- **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 Jun 2026
- **Updated:** 24 Jun 2026
- **Also known as:** BELL-CVE-2026-53039, DEBIAN-CVE-2026-53039, GHSA-5p4x-7qqv-q472, ROOT-OS-DEBIAN-11-CVE-2026-53039, ROOT-OS-DEBIAN-12-CVE-2026-53039, ROOT-OS-UBUNTU-2204-CVE-2026-53039, ROOT-OS-UBUNTU-2404-CVE-2026-53039, UBUNTU-CVE-2026-53039

## What is CVE-2026-53039?

CVE-2026-53039 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 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:

ocfs2: validate group add input before caching

[BUG]
OCFS2_IOC_GROUP_ADD can trigger a BUG_ON in
ocfs2_set_new_buffer_uptodate():

kernel BUG at fs/ocfs2/uptodate.c:509!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
RIP: 0010:ocfs2_set_new_buffer_uptodate+0x194/0x1e0 fs/ocfs2/uptodate.c:509
Code: ffffe88f 42b9fe4c 89e64889 dfe8b4df
Call Trace:
 ocfs2_group_add+0x3f1/0x1510 fs/ocfs2/resize.c:507
 ocfs2_ioctl+0x309/0x6e0 fs/ocfs2/ioctl.c:887
 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
RIP: 0033:0x7bbfb55a966d

[CAUSE]
ocfs2_group_add() calls ocfs2_set_new_buffer_uptodate() on a
user-controlled group block before ocfs2_verify_group_and_input()
validates that block number. That helper is only valid for newly
allocated metadata and asserts that the block is not already present in
the chosen metadata cache. The code also uses INODE_CACHE(inode) even
though the group descriptor belongs to main_bm_inode and later journal
accesses use that cache context instead.

[FIX]
Validate the on-disk group descriptor before caching it, then add it to
the metadata cache tracked by INODE_CACHE(main_bm_inode). Keep the
validation failure path separate from the later cleanup path so we only
remove the buffer from that cache after it has actually been inserted.
This keeps the group buffer lifetime consistent across validation,
journaling, and cleanup.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-53039?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53039?

Apply the vendor's patch.

## Is CVE-2026-53039 being exploited?

There is no known exploitation of CVE-2026-53039 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-2026-53039 and fix it if it is affected.

What it is: CVE-2026-53039 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 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-2026-53039 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-2026-53039/ (Markdown: https://insights.sbomify.com/CVE-2026-53039/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53039
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53039
- OSV: https://osv.dev/vulnerability/CVE-2026-53039

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53039/
Summaries are generated and may contain mistakes; the official description above is the record.