CVE-2026-43380 hwmon: (pmbus/q54sj108a2) fix stack overflow in debugfs read
A stack buffer overflow in the Linux kernel q54sj108a2 PMBus driver allows attackers to cause denial of service or execute arbitrary code via debugfs.
- 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-2026-43380?
CVE-2026-43380 is a high-severity memory corruption vulnerability in Linux kernel, published on 8 May 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:
hwmon: (pmbus/q54sj108a2) fix stack overflow in debugfs read
The q54sj108a2_debugfs_read function suffers from a stack buffer overflow due to incorrect arguments passed to bin2hex(). The function currently passes 'data' as the destination and 'data_char' as the source.
Because bin2hex() converts each input byte into two hex characters, a 32-byte block read results in 64 bytes of output. Since 'data' is only 34 bytes (I2C_SMBUS_BLOCK_MAX + 2), this writes 30 bytes past the end of the buffer onto the stack.
Additionally, the arguments were swapped: it was reading from the zero-initialized 'data_char' and writing to 'data', resulting in all-zero output regardless of the actual I2C read.
Fix this by: 1. Expanding 'data_char' to 66 bytes to safely hold the hex output. 2. Correcting the bin2hex() argument order and using the actual read count. 3. Using a pointer to select the correct output buffer for the final simple_read_from_buffer call.
Weakness: CWE-125
Which versions are affected by CVE-2026-43380?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43380?
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-2026-43380 being exploited?
There is no known exploitation of CVE-2026-43380 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43380, DEBIAN-CVE-2026-43380, GHSA-7c6h-fgvg-xw96, ROOT-OS-UBUNTU-2204-CVE-2026-43380, ROOT-OS-UBUNTU-2404-CVE-2026-43380, UBUNTU-CVE-2026-43380.