CVE-2026-98207

mmc: spi: reset bytes_xfered before retrying CRC failures

Published Oct 6, 2026 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4841-1 linux security update
Debian DLA Debian DLA DLA-4850-1 linux-6.12 security update
Debian DSA Debian DSA DSA-6568-1 linux security update
Ubuntu USN Ubuntu USN USN-8961-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9019-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9020-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9022-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9023-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9024-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9025-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9026-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9029-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-9039-1 Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN Ubuntu USN USN-9040-1 Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9066-1 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-9091-1 Linux kernel (NVIDIA Tegra) vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-665
Type Values Removed Values Added
Weaknesses CWE-909
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-665
Type Values Removed Values Added
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.
Title mmc: spi: reset bytes_xfered before retrying CRC failures
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 19, 2026, 9:15 AM
Reserved
Sep 25, 2026, 10:25 AM
Status
Received
Published
Oct 6, 2026, 9:18 AM
Modified
Oct 19, 2026, 10:18 AM
Severity
Moderate
Public date
Oct 6, 2026, 12:00 AM