# CVE-2026-53366: ipv4: account for fraggap on the paged allocation path

> An integer overflow in the Linux kernel IPv4 fragmentation handling can lead to memory corruption, potentially causing denial of service or code execution.

- **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:** 16 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-53366, DEBIAN-CVE-2026-53366, GHSA-r67c-r6r6-mj6m, ROOT-OS-DEBIAN-12-CVE-2026-53366, ROOT-OS-UBUNTU-2404-CVE-2026-53366, SUSE-SU-2026:3253-1, SUSE-SU-2026:3392-1, UBUNTU-CVE-2026-53366

## What is CVE-2026-53366?

CVE-2026-53366 is a high-severity vulnerability in Linux kernel, published on 16 Jul 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:

ipv4: account for fraggap on the paged allocation path

In __ip_append_data(), when the paged-allocation branch is taken,
alloclen and pagedlen are computed as

	alloclen = fragheaderlen + transhdrlen;
	pagedlen = datalen - transhdrlen;

datalen already includes fraggap, but the fraggap bytes carried over
from the previous skb are copied into the new skb's linear area at
offset transhdrlen by the subsequent skb_copy_and_csum_bits(). The
linear area is therefore undersized by fraggap bytes while pagedlen is
overstated by the same amount.

The non-paged branch sets alloclen to fraglen, which already accounts
for fraggap because datalen does. Bring the paged branch in line by
adding fraggap to alloclen and subtracting it from pagedlen.

After this adjustment, copy no longer collapses to -fraggap on the
paged path, so remove the stale comment describing that old arithmetic.

Weakness: CWE-131 (Incorrect Calculation of Buffer Size)

## Which versions are affected by CVE-2026-53366?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kernel-livepatch-SLE15-SP7-RT_Update_17` | SUSE:Linux Enterprise Live Patching 15 SP7 | All versions | 2-150700.2.1 |
| `kernel-livepatch-SLE15-SP7_Update_18` | SUSE:Linux Enterprise Live Patching 15 SP7 | All versions | 2-150700.2.1 |

Products: Linux kernel.

## How do I fix CVE-2026-53366?

Apply the vendor's patch.

## Is CVE-2026-53366 being exploited?

There is no known exploitation of CVE-2026-53366 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-2026-53366 and fix it if it is affected.

What it is: CVE-2026-53366 is a high-severity vulnerability in Linux kernel, published on 16 Jul 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-2026-53366 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-2026-53366/ (Markdown: https://insights.sbomify.com/CVE-2026-53366/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53366
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53366
- OSV: https://osv.dev/vulnerability/CVE-2026-53366

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53366/
Summaries are generated and may contain mistakes; the official description above is the record.