What is CVE-2026-16821?

CVE-2026-16821 is a high-severity vulnerability in IBM Aix, classified under Use of Externally-Controlled Format String. CVSS score: 7.0/10. Published 2026-08-28.

How severe is CVE-2026-16821?

High severity. CVSS v3 base score is 7.0 out of 10.

Vulnerability in IBM Aix

CVE-2026-16821

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a local attacker to gain elevated privileges due to a format string vulnerability.

CVSS v3 metric

CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

Affected products

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

Weakness classification (CWE)

CWE-134 — Use of Externally-Controlled Format String

References

psirt@us.ibm.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-16821?: CVE-2026-16821 is a high-severity vulnerability in IBM Aix, classified under Use of Externally-Controlled Format String. CVSS score: 7.0/10. Published 2026-08-28.
How severe is CVE-2026-16821?: High severity. CVSS v3 base score is 7.0 out of 10.