CVE-2026-18511: IBM I

High severity, CVSS 7.8. EPSS: 0.3% chance of exploitation in the next 30 days.

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a local authenticated attacker to generate a stack-based buffer overflow in the Native IBM i JSSE provider, caused by improper bounds checking during TLS session establishment. A local attacker could overflow a fixed-length buffer and execute arbitrary code on the system or cause the JVM process to crash.

Affected products

• IBM I: version 7.3 only; version 7.4 only; version 7.5 only; version 7.6 only

Published 2026-08-13. Last modified 2026-08-17.