# CVE-2026-100073: ext4: fix transaction overflow during writeback

> Insufficient transaction credit reservation in ext4 writeback can cause kernel crashes, leading to denial of service for local attackers.

- **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:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-100073, DEBIAN-CVE-2026-100073, GHSA-4m7h-6q45-6mjf, UBUNTU-CVE-2026-100073

## What is CVE-2026-100073?

CVE-2026-100073 is a medium-severity denial of service vulnerability in Linux kernel, published on 25 Sep 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:

ext4: fix transaction overflow during writeback

Commit 95ad8ee45cdb ("ext4: correct the reserved credits for extent
conversion") was correct to note that we need to reserve enough credits
for all extents possibly underlying a large folio. However it was too
eager to reduce the number of reserved credits. Extent conversion may
not only need to touch several leaf extent blocks, it may also need to
split extents - for example a single large unwritten extent may need to
be split into many small written ones in case of sparse folio dirtying.
This can thus result not only in extent leaf modifications but also in a
need to allocate new extent tree nodes. As a result the reserved
transaction credits were not sufficient in some corner cases. Use
ext4_meta_trans_blocks() for correct upper bound credit estimate.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-100073?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-100073?

Apply the vendor's patch.

## Is CVE-2026-100073 being exploited?

There is no known exploitation of CVE-2026-100073 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-2026-100073 and fix it if it is affected.

What it is: CVE-2026-100073 is a medium-severity denial of service vulnerability in Linux kernel, published on 25 Sep 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-2026-100073 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-2026-100073/ (Markdown: https://insights.sbomify.com/CVE-2026-100073/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-100073
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-100073
- OSV: https://osv.dev/vulnerability/CVE-2026-100073

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-100073/
Summaries are generated and may contain mistakes; the official description above is the record.