7.1

CVE-2025-21993: iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()

Modified
AliasesUBUNTU-CVE-2025-21993DEBIAN-CVE-2025-21993
Published 02-04-2025Last modified 11-05-2026

Vulnerability summary

CVE-2025-21993 is a high (CVSS 7.1) Out-of-bounds Read vulnerability in linux. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 12.4% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 7.1, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.1/10
010
High · v3.1 (CVE.org)
EPSS score
0.22%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 46 · Related 39
DLA-4178-1DLA-4193-1DSA-5900-1MGASA-2025-0142MGASA-2025-0146RHSA-2025:7423

Timeline

  1. 02-04-2025
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.22%

Chance of exploitation in the next 30 days

Percentile

12%

Versus all other CVEs

30-day change

Increase +0.01 pp

From 0.21% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu136 products
  • linuxAll versions (No fix recorded) | < 5.4.0-218.238 | < 5.15.0-138.148 | < 6.8.0-58.60
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 5.4.0-1147.157 | < 5.15.0-1082.89 | < 6.8.0-1027.29
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < a858cd58dea06cf85b142673deea8c5d87f11e70 | ≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < f763c82db8166e28f45b7cc4a5398a7859665940 | ≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < b388e185bfad32bfed6a97a6817f74ca00a4318f | ≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < 9bfa80c8aa4e06dff55a953c3fffbfc68a3a3b1c | ≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < 2d1eef248107bdf3d5a69d0fde04c30a79a7bf5d | ≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < b253660fac5e0e9080d2c95e3a029e1898d49afb | ≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < c1c6e527470e5eab0b2d57bd073530fbace39eab | ≥ 138fe4e069798d9aa948a5402ff15e58f483ee4e, < 07e0d99a2f701123ad3104c0f1a1e66bce74d6e5 | 2.6.26
  • linux_kernel< 6.1.132 | ≥ 6.2, < 6.6.84 | ≥ 6.7, < 6.12.20 | ≥ 6.13, < 6.13.8 | 6.14:rc1
Debian1 product
  • linux< 6.1.133-1 | < 6.12.20-1

3 vendors · 139 products

References

43 links
Show all 43 references