CVE-2025-21993: iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()
In the Linux kernel, the following vulnerability has been resolved:
iscsiibft: Fix UBSAN shift-out-of-bounds warning in ibftattrshownic()
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 Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2025-21993?
CVE-2025-21993 is classified as a moderate severity vulnerability in the Linux kernel.
How do I fix CVE-2025-21993?
To mitigate CVE-2025-21993, update to the latest version of the Linux kernel where the vulnerability has been patched.
Which versions of the Linux kernel are affected by CVE-2025-21993?
CVE-2025-21993 affects multiple versions of the Linux kernel, and specifically those that do not include the fix.
What kind of attack vector is associated with CVE-2025-21993?
CVE-2025-21993 can be exploited during iSCSI boot processes using IPv6 settings.
Is there a risk of data loss with CVE-2025-21993?
Exploitation of CVE-2025-21993 does not directly indicate a risk of data loss but could lead to denial of service conditions.