Vulnerability Details CVE-2025-39928
In the Linux kernel, the following vulnerability has been resolved:
i2c: rtl9300: ensure data length is within supported range
Add an explicit check for the xfer length to 'rtl9300_i2c_config_xfer'
to ensure the data length isn't within the supported range. In
particular a data length of 0 is not supported by the hardware and
causes unintended or destructive behaviour.
This limitation becomes obvious when looking at the register
documentation [1]. 4 bits are reserved for DATA_WIDTH and the value
of these 4 bits is used as N + 1, allowing a data length range of
1 <= len <= 16.
Affected by this is the SMBus Quick Operation which works with a data
length of 0. Passing 0 as the length causes an underflow of the value
due to:
(len - 1) & 0xf
and effectively specifying a transfer length of 16 via the registers.
This causes a 16-byte write operation instead of a Quick Write. For
example, on SFP modules without write-protected EEPROM this soft-bricks
them by overwriting some initial bytes.
For completeness, also add a quirk for the zero length.
[1] https://svanheule.net/realtek/longan/register/i2c_mst1_ctrl2
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 4.4%
CVSS Severity
CVSS v3 Score 5.5
Products affected by CVE-2025-39928
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cpe:2.3:o:linux:linux_kernel:6.13
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cpe:2.3:o:linux:linux_kernel:6.13.1
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cpe:2.3:o:linux:linux_kernel:6.13.10
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cpe:2.3:o:linux:linux_kernel:6.13.11
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cpe:2.3:o:linux:linux_kernel:6.13.12
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cpe:2.3:o:linux:linux_kernel:6.13.2
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cpe:2.3:o:linux:linux_kernel:6.13.3
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cpe:2.3:o:linux:linux_kernel:6.13.4
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cpe:2.3:o:linux:linux_kernel:6.13.5
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cpe:2.3:o:linux:linux_kernel:6.13.6
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cpe:2.3:o:linux:linux_kernel:6.13.7
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cpe:2.3:o:linux:linux_kernel:6.13.8
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cpe:2.3:o:linux:linux_kernel:6.13.9
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cpe:2.3:o:linux:linux_kernel:6.14
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cpe:2.3:o:linux:linux_kernel:6.14.1
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cpe:2.3:o:linux:linux_kernel:6.14.10
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cpe:2.3:o:linux:linux_kernel:6.14.11
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cpe:2.3:o:linux:linux_kernel:6.14.2
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cpe:2.3:o:linux:linux_kernel:6.14.3
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cpe:2.3:o:linux:linux_kernel:6.14.4
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cpe:2.3:o:linux:linux_kernel:6.14.5
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cpe:2.3:o:linux:linux_kernel:6.14.6
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cpe:2.3:o:linux:linux_kernel:6.14.7
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cpe:2.3:o:linux:linux_kernel:6.14.8
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cpe:2.3:o:linux:linux_kernel:6.14.9
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cpe:2.3:o:linux:linux_kernel:6.15
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cpe:2.3:o:linux:linux_kernel:6.15.1
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cpe:2.3:o:linux:linux_kernel:6.15.10
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cpe:2.3:o:linux:linux_kernel:6.15.11
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cpe:2.3:o:linux:linux_kernel:6.15.2
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cpe:2.3:o:linux:linux_kernel:6.15.3
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cpe:2.3:o:linux:linux_kernel:6.15.4
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cpe:2.3:o:linux:linux_kernel:6.15.5
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cpe:2.3:o:linux:linux_kernel:6.15.6
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cpe:2.3:o:linux:linux_kernel:6.15.7
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cpe:2.3:o:linux:linux_kernel:6.15.8
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cpe:2.3:o:linux:linux_kernel:6.15.9
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cpe:2.3:o:linux:linux_kernel:6.16
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cpe:2.3:o:linux:linux_kernel:6.16.1
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cpe:2.3:o:linux:linux_kernel:6.16.2
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cpe:2.3:o:linux:linux_kernel:6.16.3
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cpe:2.3:o:linux:linux_kernel:6.16.4
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cpe:2.3:o:linux:linux_kernel:6.16.5
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cpe:2.3:o:linux:linux_kernel:6.16.6
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cpe:2.3:o:linux:linux_kernel:6.16.7
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cpe:2.3:o:linux:linux_kernel:6.17