CVE-2025-21993: Linux Kernel

High severity, CVSS 7.1. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic() When performing an iSCSI boot using IPv6, iscsistart still reads the /sys/firmware/ibft/ethernetX/subnet-mask entry. Since the IPv6 prefix length is 64, this causes the shift exponent to become negative, triggering a UBSAN warning. As the concept of a subnet mask does not apply to IPv6, the value is set to ~0 to suppress the warning message.

Affected products

• Linux Linux Kernel: before 6.1.132 (fixed in 6.1.132); from 6.2, before 6.6.84 (fixed in 6.6.84); from 6.7, before 6.12.20 (fixed in 6.12.20); from 6.13, before 6.13.8 (fixed in 6.13.8); version 6.14 only

Published 2025-04-02. Last modified 2026-06-17.