CVE-2025-39680 i2c: rtl9300: Fix out-of-bounds bug in rtl9300_i2c_smbus_xfer
A local attacker can trigger an out-of-bounds read in the RTL9300 I2C driver by providing a large block size, potentially causing a crash or leaking kernel memory.
- 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-2025-39680?
CVE-2025-39680 is a high-severity memory corruption vulnerability in Linux kernel, published on 5 Sep 2025. 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:
i2c: rtl9300: Fix out-of-bounds bug in rtl9300_i2c_smbus_xfer
The data->block[0] variable comes from user. Without proper check, the variable may be very large to cause an out-of-bounds bug.
Fix this bug by checking the value of data->block[0] first.
1. commit 39244cc75482 ("i2c: ismt: Fix an out-of-bounds bug in ismt_access()") 2. commit 92fbb6d1296f ("i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()")
Weakness: CWE-125
Which versions are affected by CVE-2025-39680?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-39680?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-39680 being exploited?
There is no known exploitation of CVE-2025-39680 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-39680, DEBIAN-CVE-2025-39680, GHSA-qr79-p6wg-4p8q, UBUNTU-CVE-2025-39680.