What’s Vulnerable › Vulnerabilities

CVE-2026-89622: HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-11 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes mcp_i2c_smbus_read() stores the caller-supplied buffer pointer in mcp->rxbuf for the duration of a transfer but never clears it when the transfer finishes or times out. Once the caller frees or reuses the buffer, mcp->rxbuf becomes a dangling pointer. A delayed or spurious MCP2221_I2C_GET_DATA report can then drive mcp2221_raw_event() to memcpy device data into the freed memory, causing a write use-after-free. Route all return paths through a single exit point that clears mcp->rxbuf and mcp->rxbuf_size, so that the existing !mcp->rxbuf guard in the raw_event handler can reject any report arriving after the transfer has ended.

Affected products

• Linux: 5.7 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/03c34309eb1bce1b3b5f7c4a94b703f419120383
• https://git.kernel.org/stable/c/198bf4a226229e36dfe254493a45c71c3ffc7e57
• https://git.kernel.org/stable/c/968546b676d992dd1da3e057d40598231f725996
• https://git.kernel.org/stable/c/bd146a8ff107c6d77e75597decbcd1df0d7900d6
• https://git.kernel.org/stable/c/d6c6b293173c0ea87189501cbd77e8fa677814a1
• https://git.kernel.org/stable/c/db2333f88729c8aae062cb171ed058725ff5c901

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