What is CVE-2026-16866?

CVE-2026-16866 is a medium-severity vulnerability in IBM Aix, classified under Out-of-bounds Read. CVSS score: 4.8/10. Published 2026-08-19.

How severe is CVE-2026-16866?

Medium severity. CVSS v3 base score is 4.8 out of 10.

Out-of-bounds Read in IBM Aix

CVE-2026-16866

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a remote attacker to cause a denial of service due to an out-of-bounds read.

Vulnerability class: Buffer Overflow

Published 2026-08-19 · last modified 2026-08-20.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.003 (25.2th percentile), scored 2026-10-06.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.001

Affected products

IBM Aix — versions 7.2, 7.3
IBM Powervm Vios — versions 4.1
IBM Vios

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

www.ibm.com/support/pages/node/7283858 (vendor-advisory, Patch, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-16866?: CVE-2026-16866 is a medium-severity vulnerability in IBM Aix, classified under Out-of-bounds Read. CVSS score: 4.8/10. Published 2026-08-19.
How severe is CVE-2026-16866?: Medium severity. CVSS v3 base score is 4.8 out of 10.