CVE-2026-17003 is a high severity (CVSS 7.7) out-of-bounds write in IBM AIX 7.2 and 7.3 and PowerVM VIOS 4.1. A remote attacker could compromise confidentiality and integrity. IBM fixed it in cumulative service packs and fix packs, so move each system to the level in the bulletin.
What's affected
IBM AIX 7.2 and 7.3, and IBM PowerVM VIOS 4.1. IBM's bulletin is a shared one that lists many AIX and VIOS vulnerabilities, and its change history shows an initial publication on 15 August 2026. The affected fileset is bos.mp64 at these levels:
- AIX 7.2.5: 7.2.5.0 to 7.2.5.212
- AIX 7.3.2: 7.3.2.0 to 7.3.2.5
- AIX 7.3.3: 7.3.3.0 to 7.3.3.2
- AIX 7.3.4: 7.3.4.0 to 7.3.4.1
IBM's remediation levels are AIX 7.2 TL05 SP13, 7.3 TL02 SP5, 7.3 TL03 SP3 and 7.3 TL04 SP2, and VIOS fix packs 4.1.0.50, 4.1.1.30 and 4.1.2.20. These service packs are cumulative. IBM lists no workaround or mitigation.
How to check if you're exposed
Check the AIX level and the affected fileset on each LPAR.
oslevel -s
lslpp -L | grep -i bos.mp64
On a VIOS, run ioslevel as padmin. If the bos.mp64 level falls in one of the ranges above, the system is affected. IBM also assigns APARs: IJ59566 for AIX 7.2.5, IJ59565 for 7.3.2, IJ59564 for 7.3.3 and IJ59563 for 7.3.4.
What to do now
- List every AIX LPAR and VIOS, with its technology level and service pack.
- Download the service pack or fix pack for your level from IBM Fix Central.
- Plan the LPAR reboot, or use Live Update on AIX where it fits, because IBM says a reboot is needed to complete the update.
- Read IBM's notes on nimsh secure and, for VIOS 4.1.0 and 4.1.1, the post-update steps for the Postgres15 migration.
- Recheck
oslevel -safter the update and record it.
Why it matters
The weakness is CWE-787 (Out-of-bounds Write). Writing outside a buffer can corrupt memory the program did not mean to change. IBM says a remote attacker could compromise the confidentiality and integrity of the system.
The vector marks complexity as high, with no privileges and no user interaction, and low availability impact. Because IBM rolls many AIX fixes into one cumulative service pack, you rarely need to patch for a single CVE. Aim for the listed level and you pick up the rest. CISA does not list this CVE as known exploited.
Quick check
Is the fix specific to this CVE?
No. IBM lists cumulative service packs and fix packs that include fixes for earlier security issues too.
Sources
Last reviewed: 19 October 2026.
