CVE-2026-74515 KVM: s390: pci: Reject adapter interrupt forwarding if already enabled
A missing check in KVM s390 PCI allows resource leaks via repeated interrupt forwarding requests, potentially causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74515?
CVE-2026-74515 is a high-severity denial of service vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
KVM: s390: pci: Reject adapter interrupt forwarding if already enabled
The MPCIFC instruction doesn't allow registering adapter interrupts without first unregistering. So reject any request to enable interrupt forwarding if its already enabled for the zPCI device. This also fixes overwriting and thus leaking resources when the ioctl is called multiple times for the same device.
Which versions are affected by CVE-2026-74515?
Linux distribution packages (37)
bpftool AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-abi-stablelists AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-core AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-cross-headers AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-debug AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-debug-core AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-debug-devel AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-debug-modules AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-debug-modules-extra AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-devel AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-doc AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-headers AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-modules AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-modules-extra AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-rt AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-core AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-debug AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-debug-core AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-debug-devel AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-debug-modules AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-debug-modules-extra AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-devel AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-modules AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-rt-modules-extra AlmaLinux:8 | All versions | 4.18.0-553.179.1.rt7.520.el8_10 |
kernel-tools AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-tools-libs AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-tools-libs-devel AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-zfcpdump AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-zfcpdump-core AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-zfcpdump-devel AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-zfcpdump-modules AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel-zfcpdump-modules-extra AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
perf AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
python3-perf AlmaLinux:8 | All versions | 4.18.0-553.179.1.el8_10 |
kernel Rocky Linux:8 | All versions | 0:4.18.0-553.179.1.el8_10 |
kernel-rt Rocky Linux:8 | All versions | 0:4.18.0-553.179.1.rt7.520.el8_10 |
How do I fix CVE-2026-74515?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-74515 being exploited?
There is no known exploitation of CVE-2026-74515 in the wild and no public exploit code.
Sources
Also known as ALSA-2026:89814, ALSA-2026:89816, BELL-CVE-2026-74515, DEBIAN-CVE-2026-74515, GHSA-269x-pqmw-g2f4, RLSA-2026:89814 and 2 more.