# CVE-2026-72098: dm-verity: fix buffer overflow in FEC calculation

> A buffer overflow in the Linux kernel's dm-verity FEC calculation allows out-of-bounds writes, potentially leading to code execution or privilege escalation.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-96362, BELL-CVE-2026-72098, DEBIAN-CVE-2026-72098, GHSA-h569-8r6w-7rvq, UBUNTU-CVE-2026-72098

## What is CVE-2026-72098?

CVE-2026-72098 is a critical memory corruption vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

dm-verity: fix buffer overflow in FEC calculation

There's a buffer overflow in dm-verity-fec:

if (neras && *neras <= v->fec->roots)
	fio->erasures[(*neras)++] = i;

This allows *neras to reach roots + 1 (the post-increment pushes it past
roots). This value is then passed as no_eras to decode_rs8(). Inside the
RS decoder (lib/reed_solomon/decode_rs.c:113-121), the erasure locator
polynomial loop writes lambda[j] where j can reach nroots + 1 — one
element past the end of lambda[] (which is sized nroots + 1, valid
indices 0..nroots). The out-of-bounds write lands on syn[0], corrupting
the syndrome buffer.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-72098?


## How do I fix CVE-2026-72098?

Apply the vendor's patch.

## Is CVE-2026-72098 being exploited?

There is no known exploitation of CVE-2026-72098 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72098 and fix it if it is affected.

What it is: CVE-2026-72098 is a critical memory corruption vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72098 in the wild and no public exploit code.

Affected product: Linux. 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-2026-72098/ (Markdown: https://insights.sbomify.com/CVE-2026-72098/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72098
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72098
- OSV: https://osv.dev/vulnerability/CVE-2026-72098

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72098/
Summaries are generated and may contain mistakes; the official description above is the record.