# CVE-2026-98207: mmc: spi: reset bytes_xfered before retrying CRC failures

> A flaw in the Linux kernel MMC SPI driver allows attackers to read stale data from previous failed transfers due to incorrect byte counting during CRC error retries.

- **Severity:** Not scored
- **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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106002, BELL-CVE-2026-98207, DEBIAN-CVE-2026-98207, GHSA-gx8r-25rx-rh7g, UBUNTU-CVE-2026-98207

## What is CVE-2026-98207?

CVE-2026-98207 is a vulnerability in Linux, published on 6 Oct 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:

mmc: spi: reset bytes_xfered before retrying CRC failures

mmc_spi_data_do() updates data->bytes_xfered after each block has been
transferred successfully.  If a later block in the same data request
fails with a CRC error, data->bytes_xfered may therefore contain the
number of bytes completed before the failing block.

mmc_spi_request() has a private recovery path for such CRC failures.  It
sends STOP_TRANSMISSION, clears data->error and jumps back to
crc_recover to issue the same command and data request again.  However,
it does not clear data->bytes_xfered before the retry.

If the retry succeeds, the request is completed with the bytes from the
failed attempt still included in data->bytes_xfered.  For a multi-block
request this can make the completed request report more bytes than were
transferred by the successful retry, and can even exceed the request size
when most blocks completed before the CRC error.

This is most likely to be observed on MMC-over-SPI systems where long
multi-block transfers occasionally hit a data CRC error but the
mmc_spi-internal retry succeeds.  The data itself is retried, but the
completion accounting is not.

Clear data->bytes_xfered together with data->error before repeating the
request so the final completion reports only the bytes transferred by the
successful attempt.

## Which versions are affected by CVE-2026-98207?


## How do I fix CVE-2026-98207?

Apply the vendor's patch.

## Is CVE-2026-98207 being exploited?

There is no known exploitation of CVE-2026-98207 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98207 and fix it if it is affected.

What it is: CVE-2026-98207 is a vulnerability in Linux, published on 6 Oct 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-2026-98207 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-2026-98207/ (Markdown: https://insights.sbomify.com/CVE-2026-98207/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98207
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98207
- OSV: https://osv.dev/vulnerability/CVE-2026-98207

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98207/
Summaries are generated and may contain mistakes; the official description above is the record.