CVE-2026-89622 HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes
A use-after-free in the Linux kernel MCP2221 HID driver allows attackers to execute arbitrary code or escalate privileges via crafted I2C reports.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89622?
CVE-2026-89622 is a high-severity use after free vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-89622?
How do I fix CVE-2026-89622?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-89622 being exploited?
There is no known exploitation of CVE-2026-89622 in the wild and no public exploit code.
Sources
Also known as AZL-100335, BELL-CVE-2026-89622, DEBIAN-CVE-2026-89622, GHSA-hmph-x79p-jwjq, UBUNTU-CVE-2026-89622.