CVE-2026-63959 usb: typec: tcpm/tcpci_maxim: validate header NDO against RX_BYTE_CNT
A malicious USB port can cause the Linux kernel to read uninitialized stack memory, potentially leaking sensitive information.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63959?
CVE-2026-63959 is a vulnerability in Linux, published on 19 Jul 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:
usb: typec: tcpm/tcpci_maxim: validate header NDO against RX_BYTE_CNT
A broken/malicious port can transmit a CRC-valid frame whose header advertises up to seven data objects but whose body carries fewer than that. Check for this, and rightfully reject the message, instead of reading from uninitialized stack memory.
Which versions are affected by CVE-2026-63959?
How do I fix CVE-2026-63959?
Apply the vendor's patch.
Is CVE-2026-63959 being exploited?
There is no known exploitation of CVE-2026-63959 in the wild and no public exploit code.
Sources
Also known as AZL-92739, BELL-CVE-2026-63959, DEBIAN-CVE-2026-63959, GHSA-fwcg-qvj5-vv4j, ROOT-OS-DEBIAN-11-CVE-2026-63959, ROOT-OS-DEBIAN-12-CVE-2026-63959 and 2 more.