In Eclipse OpenJ9 versions prior to 0.63.0, the JITServer component is vulnerable to a pre-authentication remote denial of service. When processing the initial 4-byte length field of an incoming TCP connection, an integer overflow in `MessageBuffer::computeRequiredCapacity()` causes the receiving compilation worker thread to enter an infinite loop consuming ~100% CPU. An unauthenticated remote attacker can exploit this by opening a small number of crafted TCP connections to exhaust the entire worker thread pool, silently halting compilation services for all connected client JVMs.
https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/940
https://gitlab.eclipse.org/security/cve-assignment/-/work_items/422
Published: 2026-10-21
Updated: 2026-10-22
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P
Severity: Medium
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity: High
Base Score: 8.7
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00421