# 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. - **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`) - **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:** Yes - **Published:** 15 Aug 2026 - **Updated:** 16 Oct 2026 - **Also known as:** ALSA-2026:89814, ALSA-2026:89816, BELL-CVE-2026-74515, DEBIAN-CVE-2026-74515, GHSA-269x-pqmw-g2f4, RLSA-2026:89814, RLSA-2026:89816, UBUNTU-CVE-2026-74515 ## 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? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `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. ## Is CVE-2026-74515 being exploited? There is no known exploitation of CVE-2026-74515 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-74515 and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of CVE-2026-74515 in the wild and no public exploit code. Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-74515/ (Markdown: https://insights.sbomify.com/CVE-2026-74515/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74515 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74515 - OSV: https://osv.dev/vulnerability/CVE-2026-74515 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-74515/ Summaries are generated and may contain mistakes; the official description above is the record.