CVE-2025-39928 (GCVE-0-2025-39928)

Vulnerability from cvelistv5 – Published: 2025-10-01 08:07 – Updated: 2026-08-05 12:06
VLAI
Title
i2c: rtl9300: ensure data length is within supported range
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
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-01-14 17:39 UTC
CWE
  • CWE-191 - Integer Underflow (Wrap or Wraparound)
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6639 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c366be720235301fdadf67e6f1ea6ff32669c074 , < c91382328fc89f73144d5582f2d8f1dd3e41c8f7 (git)
Affected: c366be720235301fdadf67e6f1ea6ff32669c074 , < 06418cb5a1a542a003fdb4ad8e76ea542d57cfba (git)
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Linux Linux Affected: 6.13
Unaffected: 0 , < 6.13 (semver)
Unaffected: 6.16.8 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ni2c: rtl9300: asegurar que la longitud de los datos est\u00e9 dentro del rango soportado\n\nA\u00f1adir una verificaci\u00f3n expl\u00edcita para la longitud de la transferencia a \u0027rtl9300_i2c_config_xfer\u0027 para asegurar que la longitud de los datos est\u00e9 dentro del rango soportado. En particular, una longitud de datos de 0 no es soportada por el hardware y causa un comportamiento no deseado o destructivo.\n\nEsta limitaci\u00f3n se hace obvia al observar la documentaci\u00f3n del registro [1]. 4 bits est\u00e1n reservados para DATA_WIDTH y el valor de estos 4 bits se usa como N + 1, permitiendo un rango de longitud de datos de 1 \u003c= len menor o igual que 16.\n\nAfectada por esto es la Operaci\u00f3n R\u00e1pida SMBus que funciona con una longitud de datos de 0. Pasar 0 como longitud causa un desbordamiento negativo del valor debido a:\n\n(len - 1) \u0026 0xf\n\ny especificando efectivamente una longitud de transferencia de 16 a trav\u00e9s de los registros. Esto causa una operaci\u00f3n de escritura de 16 bytes en lugar de una Escritura R\u00e1pida. Por ejemplo, en m\u00f3dulos SFP sin EEPROM protegida contra escritura, esto los inutiliza parcialmente al sobrescribir algunos bytes iniciales.\n\nPara completar, a\u00f1adir tambi\u00e9n una peculiaridad para la longitud cero.\n\n[1] HTTPS://svanheule.net/realtek/longan/register/i2c_mst1_ctrl2"
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                    "timestamp": "2026-01-14T17:39:24.283668Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "problemTypes": [
              {
                "descriptions": [
                  {
                    "cweId": "CWE-191",
                    "description": "CWE-191 Integer Underflow (Wrap or Wraparound)",
                    "lang": "en",
                    "type": "CWE"
                  }
                ]
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-01-14T17:39:19.625Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "Linux",
              "programFiles": [
                "drivers/i2c/busses/i2c-rtl9300.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "lessThan": "c91382328fc89f73144d5582f2d8f1dd3e41c8f7",
                  "status": "affected",
                  "version": "c366be720235301fdadf67e6f1ea6ff32669c074",
                  "versionType": "git"
                },
                {
                  "lessThan": "06418cb5a1a542a003fdb4ad8e76ea542d57cfba",
                  "status": "affected",
                  "version": "c366be720235301fdadf67e6f1ea6ff32669c074",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "drivers/i2c/busses/i2c-rtl9300.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "6.13"
                },
                {
                  "lessThan": "6.13",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "6.16.*",
                  "status": "unaffected",
                  "version": "6.16.8",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "6.17",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.16.8",
                      "versionStartIncluding": "6.13",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.17",
                      "versionStartIncluding": "6.13",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "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"
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.1,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
                "version": "3.1"
              }
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-07-30T05:58:30.740Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/c91382328fc89f73144d5582f2d8f1dd3e41c8f7"
            },
            {
              "url": "https://git.kernel.org/stable/c/06418cb5a1a542a003fdb4ad8e76ea542d57cfba"
            }
          ],
          "title": "i2c: rtl9300: ensure data length is within supported range",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-39928",
        "datePublished": "2025-10-01T08:07:15.530Z",
        "dateReserved": "2025-04-16T07:20:57.147Z",
        "dateUpdated": "2026-07-30T05:58:30.740Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.