CVE-2025-21993: iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()
First published: Wed Apr 02 2025(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Linux Kernel | <6.1.132 | |
| Linux Kernel | >=6.2<6.6.84 | |
| Linux Kernel | >=6.7<6.12.20 | |
| Linux Kernel | >=6.13<6.13.8 | |
| Linux Kernel | =6.14-rc1 |
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Reference Links
- https://git.kernel.org/stable/c/07e0d99a2f701123ad3104c0f1a1e66bce74d6e5
- https://git.kernel.org/stable/c/2d1eef248107bdf3d5a69d0fde04c30a79a7bf5d
- https://git.kernel.org/stable/c/9bfa80c8aa4e06dff55a953c3fffbfc68a3a3b1c
- https://git.kernel.org/stable/c/b253660fac5e0e9080d2c95e3a029e1898d49afb
- https://git.kernel.org/stable/c/c1c6e527470e5eab0b2d57bd073530fbace39eab
- https://git.kernel.org/stable/c/a858cd58dea06cf85b142673deea8c5d87f11e70
- https://git.kernel.org/stable/c/f763c82db8166e28f45b7cc4a5398a7859665940
- https://git.kernel.org/stable/c/b388e185bfad32bfed6a97a6817f74ca00a4318f
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.
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