What is CVE-2026-16839?

CVE-2026-16839 is a critical-severity vulnerability in IBM Aix, classified under Out-of-bounds Read. CVSS score: 9.4/10. Published 2026-08-19.

How severe is CVE-2026-16839?

Critical severity. CVSS v3 base score is 9.4 out of 10.

Out-of-bounds Read in IBM Aix

CVE-2026-16839

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 could allow a remote attacker to obtain sensitive information due to an integer underflow in the IPv4 IP-options parser.

Vulnerability class: Buffer Overflow

Published 2026-08-19 · last modified 2026-08-24.

CVSS v3 metric

CVSS v3 base score 9.4 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (42.3th percentile), scored 2026-10-06.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 42.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · 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-2026-16839?: CVE-2026-16839 is a critical-severity vulnerability in IBM Aix, classified under Out-of-bounds Read. CVSS score: 9.4/10. Published 2026-08-19.
How severe is CVE-2026-16839?: Critical severity. CVSS v3 base score is 9.4 out of 10.