Buffer overflow in IBM I

CVE-2026-17255

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service due to improper validation of the prefix length in ICMPv6 Router Advertisements.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.004 (33.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 33.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-17255: held from 0.004 to 0.004.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

  • IBM I — versions 7.3, 7.4, 7.5

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-17255?
CVE-2026-17255 is a medium-severity vulnerability in IBM I, classified under Out-of-bounds Write. CVSS score: 4.3/10. Published 2026-09-04.
How severe is CVE-2026-17255?
Medium severity. CVSS v3 base score is 4.3 out of 10.