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CVE-2025-21993

HIGHCVSS 7.1/10EPSS 0.19%

Last modified

CVE-2025-21993 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS Probability
0.19%

8.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersionsUpdate
LinuxLinux Kernel< 6.1.132—
LinuxLinux Kernel>= 6.2, < 6.6.84—
LinuxLinux Kernel>= 6.7, < 6.12.20—
LinuxLinux Kernel>= 6.13, < 6.13.8—
LinuxLinux Kernel6.14Rc1

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2025-21993?
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.
How severe is CVE-2025-21993?
CVE-2025-21993 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.
How do I fix CVE-2025-21993?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-21993?

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Source: NVD / NIST