CVE-2026-31623 net: usb: cdc-phonet: fix skb frags[] overflow in rx_complete()
A malicious USB device can overflow kernel memory buffers in the CDC Phonet driver, potentially allowing code execution or system crashes.
- 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-2026-31623?
CVE-2026-31623 is a medium-severity memory corruption vulnerability in Linux kernel, published on 24 Apr 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:
net: usb: cdc-phonet: fix skb frags[] overflow in rx_complete()
A malicious USB device claiming to be a CDC Phonet modem can overflow the skb_shared_info->frags[] array by sending an unbounded sequence of full-page bulk transfers.
Drop the skb and increment the length error when the frag limit is reached. This matches the same fix that commit f0813bcd2d9d ("net: wwan: t7xx: fix potential skb->frags overflow in RX path") did for the t7xx driver.
Weakness: CWE-120
Which versions are affected by CVE-2026-31623?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31623?
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-2026-31623 being exploited?
There is no known exploitation of CVE-2026-31623 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-83780, BELL-CVE-2026-31623, DEBIAN-CVE-2026-31623, GHSA-76f4-xjp9-xcxc, ROOT-OS-DEBIAN-11-CVE-2026-31623, ROOT-OS-DEBIAN-12-CVE-2026-31623 and 4 more.