CVE-2026-31616 usb: gadget: f_phonet: fix skb frags[] overflow in pn_rx_complete()
A malicious USB host can trigger a heap buffer overflow in the Linux kernel Phonet gadget driver, potentially leading to code execution or system crash.
- 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-2026-31616?
CVE-2026-31616 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:
usb: gadget: f_phonet: fix skb frags[] overflow in pn_rx_complete()
A broken/bored/mean USB host can overflow the skb_shared_info->frags[] array on a Linux gadget exposing a Phonet function by sending an unbounded sequence of full-page OUT transfers.
pn_rx_complete() finalizes the skb only when req->actual < req->length, where req->length is set to PAGE_SIZE by the gadget. If the host always sends exactly PAGE_SIZE bytes per transfer, fp->rx.skb will never be reset and each completion will add another fragment via skb_add_rx_frag(). Once nr_frags exceeds MAX_SKB_FRAGS (default 17), subsequent frag stores overwrite memory adjacent to the shinfo on the heap.
Drop the skb and account a length error when the frag limit is reached, matching the fix applied in t7xx by commit f0813bcd2d9d ("net: wwan: t7xx: fix potential skb->frags overflow in RX path").
Weakness: CWE-401
Which versions are affected by CVE-2026-31616?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31616?
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-2026-31616 being exploited?
There is no known exploitation of CVE-2026-31616 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31616, DEBIAN-CVE-2026-31616, GHSA-h96r-xqwg-w67w, ROOT-OS-DEBIAN-11-CVE-2026-31616, ROOT-OS-DEBIAN-12-CVE-2026-31616, ROOT-OS-UBUNTU-2204-CVE-2026-31616 and 2 more.