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.
{
"cna_assigner": "Linux",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21993.json"
}"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21993.json"
[
{
"signature_version": "v1",
"target": {
"file": "drivers/firmware/iscsi_ibft.c",
"function": "ibft_attr_show_nic"
},
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@c1c6e527470e5eab0b2d57bd073530fbace39eab",
"deprecated": false,
"digest": {
"function_hash": "186383060437671382199209691466313715284",
"length": 1519.0
},
"id": "CVE-2025-21993-1c3fc43d",
"signature_type": "Function"
},
{
"signature_version": "v1",
"id": "CVE-2025-21993-eb2f2cc5",
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@c1c6e527470e5eab0b2d57bd073530fbace39eab",
"signature_type": "Line",
"target": {
"file": "drivers/firmware/iscsi_ibft.c"
},
"deprecated": false,
"digest": {
"line_hashes": [
"257265890474634735705923564800699978585",
"36909797975205229295889020985457683427",
"251089248995704583156479251151190829013",
"314297912961110966264198032225138884710"
],
"threshold": 0.9
}
}
]