CVE-2026-16904 is a high severity (CVSS 8.1) improper privilege management flaw in IBM i 7.3, 7.4, 7.5 and 7.6, in monitor owner reassignment. A remote authenticated attacker could execute arbitrary commands. IBM provides a PTF for each release under 5770-SS1 Option 3, and the bulletin lists the numbers.
What's affected
IBM i 7.6, 7.5, 7.4 and 7.3, per IBM's bulletin and the NVD record. IBM lists these PTFs for 5770-SS1 Option 3:
- IBM i 7.6: SJ10887
- IBM i 7.5: SJ10888
- IBM i 7.4: SJ10890
- IBM i 7.3: SJ10891
IBM says to address the issue now and recommends that users of unsupported IBM i releases move to a supported, fixed version.
How to check if you're exposed
IBM i 7.3 through 7.6 are all in scope, so every supported and recently supported release needs a look. On each partition, confirm the installed release and then check whether the PTF for your release is loaded. From a command line:
DSPPTF LICPGM(5770SS1)
Look for the PTF number listed for your release in the table above, with a status of Applied or Permanently applied. You can also use option 10 of GO LICPGM to confirm the release. Do this on every LPAR, including test and recovery systems, because they are often patched last.
What to do now
- List every IBM i partition and its release, including test and disaster recovery systems.
- Find the PTF for your release in the table above, and order it from IBM Fix Central or through your usual PTF process.
- Apply the PTF and restart as the PTF cover letter requires.
- Check the PTF status with DSPPTF and record it.
- Limit access to IBM i network services to the hosts and users that need them.
Why it matters
CWE-269 is improper privilege management. When ownership of a monitor changes, privileges are not handled correctly, and a signed-in user can end up able to run commands they should not. The vector shows low complexity and low privileges, with high confidentiality and integrity impact.
This bulletin is large. It lists many IBM i issues with scores from 3.0 to 9.6, including CVE-2026-17094. One set of PTFs per release addresses the bulletin, so check which of your systems still lack it.
The weakness class here is CWE-269 (Improper Privilege Management). The NVD record scores it 8.1, which is high severity. IBM's bulletin gives the same score. The CVSS vector reads attack vector over the network, low attack complexity, low privileges required, no user interaction. Scope is unchanged. Impact on confidentiality, integrity and availability is rated high, high and none. The record's KEV flag is false, so this CVE is not in CISA's Known Exploited Vulnerabilities catalog, and the advisory I fetched does not report exploitation.
Safeguard's Gold directory tracks this CVE, and reachability analysis helps you decide which affected components matter most for your own software.
Quick check
Does this need a valid IBM i user profile?
Yes. The record shows low privileges required, so the attacker needs a signed-in profile.
Sources
- IBM security bulletin
- Safeguard Gold entry for CVE-2026-16904, which summarizes the NVD record
Last reviewed: 18 October 2026.
