CVE-2026-18821
HIGH 7.5IBM PowerVM Hypervisor FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, and FW950.00 through FW950.H2 Power Systems Firmware is affected by a vulnerability in partition firmware during network boot. An unauthenticated attacker on the same network as a partition undergoing network boot can send a malformed packet, allowing arbitrary code to be executed in the partition firmware and compromising everything subsequently loaded by that partition. Other partitions and the managed system are not affected. Only partitions actively performing a network boot are affected, resulting in a confidentiality, integrity, and availability impact.
Severe if exploited (CVSS 7.5), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.2%chance of exploitation in 30 days · 9th percentile
Impact if exploited
7.5CVSS 3.1 · HIGH
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ⚠Access: Must sit on the same / adjacent network
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ⚠Complexity: Needs a race window or specific setup
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-18821/poc.jsonMachine-readable PoC index for this CVE (for automation).Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-18821/poc.json
Weakness (CWE)
- CWE-787: Out-of-bounds Write
CVSS vector
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
All CVSS metrics
- HIGH 7.5 v3.1 · CNA Primary
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - HIGH 7.5 v3.1 · NVD Secondary
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H