fkie_cve-2025-39928
Vulnerability from fkie_nvd
Published
2025-10-01 08:15
Modified
2025-12-10 21:50
Severity ?
Summary
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
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 | |
| linux | linux_kernel | 6.17 |
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: rtl9300: ensure data length is within supported range\n\nAdd an explicit check for the xfer length to \u0027rtl9300_i2c_config_xfer\u0027\nto ensure the data length isn\u0027t within the supported range. In\nparticular a data length of 0 is not supported by the hardware and\ncauses unintended or destructive behaviour.\n\nThis limitation becomes obvious when looking at the register\ndocumentation [1]. 4 bits are reserved for DATA_WIDTH and the value\nof these 4 bits is used as N + 1, allowing a data length range of\n1 \u003c= len \u003c= 16.\n\nAffected by this is the SMBus Quick Operation which works with a data\nlength of 0. Passing 0 as the length causes an underflow of the value\ndue to:\n\n(len - 1) \u0026 0xf\n\nand effectively specifying a transfer length of 16 via the registers.\nThis causes a 16-byte write operation instead of a Quick Write. For\nexample, on SFP modules without write-protected EEPROM this soft-bricks\nthem by overwriting some initial bytes.\n\nFor completeness, also add a quirk for the zero length.\n\n[1] https://svanheule.net/realtek/longan/register/i2c_mst1_ctrl2"
}
],
"id": "CVE-2025-39928",
"lastModified": "2025-12-10T21:50:13.647",
"metrics": {
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"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
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"published": "2025-10-01T08:15:36.230",
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"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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