In the Linux kernel, the following vulnerability has been resolved:

xfrm: iptfs: validate inner IPv4 header length in IPTFS payload

Add validation of the inner IPv4 packet tot_len and ihl fields parsed
from decrypted IPTFS payloads in __input_process_payload(). A crafted
ESP packet containing an inner IPv4 header with tot_len=0 causes an
infinite loop: iplen=0 leads to capturelen=min(0, remaining)=0, so the
data offset never advances and the while(data < tail) loop never
terminates, spinning forever in softirq context.

Reject inner IPv4 packets where tot_len < ihl4 or ihl4 < sizeof(struct
iphdr), which catches both the tot_len=0 case and malformed ihl values.
The normal IP stack performs this validation in ip_rcv_core(), but IPTFS
extracts and processes inner packets before they reach that layer.

References

• https://nvd.nist.gov/vuln/detail/CVE-2026-31472
• https://git.kernel.org/stable/c/0d10393d5eac33cbd92f7a41fddca12c41d3cb7e
• https://git.kernel.org/stable/c/3db7d4f777a00164582061ccaa99569cd85011a3
• https://git.kernel.org/stable/c/de6d8e8ce5187f7402c9859b443355e7120c5f09