Integer overflow in IBM I

CVE-2026-18671

IBM i 7.6, 7.5, 7.4, and 7.3 could allow an authenticated attacker to force a NetServer server thread exception, caused by an integer overflow during bounds checking in request processing. The attacker could exploit this vulnerability to cause a temporary denial of service.

Vulnerability class: Integer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L.

EPSS exploit prediction

EPSS: 0.004 (27.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.0% 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-2026-18671: held from 0.002 to 0.004.

EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.001

Affected products

  • IBM I — versions 7.6, 7.5, 7.4

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-18671?
CVE-2026-18671 is a medium-severity vulnerability in IBM I, classified under Integer Overflow or Wraparound. CVSS score: 6.5/10. Published 2026-08-13.
How severe is CVE-2026-18671?
Medium severity. CVSS v3 base score is 6.5 out of 10.