CVE-2025-21993

High

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.

Package Linux Kernel
Published 2025-04-02
Last modified 2025-11-03
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.1

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Weakness type

CWE-125

CVE-2025-21993 is a Out-of-bounds Read vulnerability

What is Out-of-bounds Read?

The product reads data past the end or before the beginning of the intended buffer. Learn more on MITRE CWE

Affected versions

Linux kernel versions 2.6.26 and later are affected. Fixed in 5.4.292, 5.10.236, 5.15.180, 6.1.132, 6.6.84, 6.12.20, 6.13.8, 6.14 and their respective stable series.

Affected from
≥ 2.6.26
Fixed in
✓ 5.4.292 5.4.x ✓ 5.10.236 5.10.x ✓ 5.15.180 5.15.x ✓ 6.1.132 6.1.x ✓ 6.6.84 6.6.x ✓ 6.12.20 6.12.x ✓ 6.13.8 6.13.x ✓ 6.14

References

The following references provide additional information about CVE-2025-21993 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

8 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2025-21993?

    CVE-2025-21993 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10 , classified as an Out-of-bounds Read flaw (CWE-125) . It affects Linux kernel versions from 2.6.26 onward and has been patched in 5.4.292, 5.10.236, 5.15.180 and others. CVE-2025-21993 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-21993?

    CVE-2025-21993 has a CVSS score of 7.1 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H .

  • Is there a patch available for CVE-2025-21993?

    Yes — CVE-2025-21993 has been patched. Fixed versions include 5.4.292, 5.10.236, 5.15.180 and others. If you are running Linux kernel 2.6.26 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-21993 actively exploited?

    No — CVE-2025-21993 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Out-of-bounds Read (CWE-125)?

    The product reads data past the end or before the beginning of the intended buffer. View CWE-125 on MITRE CWE →

Back to
All CVEs
View on
NVD / NIST