# CVE-2025-39718: vsock/virtio: Validate length in packet header before skb_put() > A missing length validation in the Linux kernel vsock/virtio driver allows a malicious host to cause memory corruption in the guest. - **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 5 Sep 2025 - **Updated:** 15 Oct 2026 - **Also known as:** ALSA-2025:21397, ALSA-2025:21398, AZL-66947, BELL-CVE-2025-39718, DEBIAN-CVE-2025-39718, GHSA-4whh-7h4c-xh74, RHSA-2025:21397, RHSA-2025:21398, ROOT-OS-DEBIAN-12-CVE-2025-39718, ROOT-OS-DEBIAN-13-CVE-2025-39718, ROOT-OS-UBUNTU-2404-CVE-2025-39718, UBUNTU-CVE-2025-39718 ## What is CVE-2025-39718? CVE-2025-39718 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 5 Sep 2025. 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: vsock/virtio: Validate length in packet header before skb_put() When receiving a vsock packet in the guest, only the virtqueue buffer size is validated prior to virtio_vsock_skb_rx_put(). Unfortunately, virtio_vsock_skb_rx_put() uses the length from the packet header as the length argument to skb_put(), potentially resulting in SKB overflow if the host has gone wonky. Validate the length as advertised by the packet header before calling virtio_vsock_skb_rx_put(). Weakness: CWE-787 (Out-of-bounds Write) ## Which versions are affected by CVE-2025-39718? It affects 2 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `bpftool` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-abi-stablelists` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-core` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-cross-headers` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-debug` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-debug-core` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-debug-devel` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-debug-modules` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-debug-modules-extra` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-devel` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-doc` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-headers` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-modules` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-modules-extra` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-rt` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-core` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-debug` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-debug-core` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-debug-devel` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-debug-modules` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-debug-modules-extra` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-devel` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-modules` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-rt-modules-extra` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.rt7.425.el8_10 | | `kernel-tools` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-tools-libs` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-tools-libs-devel` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-zfcpdump` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-zfcpdump-core` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-zfcpdump-devel` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-zfcpdump-modules` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `kernel-zfcpdump-modules-extra` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `perf` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `python3-perf` | AlmaLinux:8 | All versions | 4.18.0-553.84.1.el8_10 | | `bpftool` | Red Hat:enterprise_linux:8::baseos | All versions | 0:4.18.0-553.84.1.el8_10 | | `bpftool-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:4.18.0-553.84.1.el8_10 | | `kernel` | Red Hat:enterprise_linux:8::baseos | All versions | 0:4.18.0-553.84.1.el8_10 | | `kernel-abi-stablelists` | Red Hat:enterprise_linux:8::baseos | All versions | 0:4.18.0-553.84.1.el8_10 | | `kernel-core` | Red Hat:enterprise_linux:8::baseos | All versions | 0:4.18.0-553.84.1.el8_10 | Products: Debian Debian Linux, Linux kernel. ## How do I fix CVE-2025-39718? Apply the vendor's patch. ## Is CVE-2025-39718 being exploited? There is no known exploitation of CVE-2025-39718 in the wild and no public exploit code. ## Other vulnerabilities in Debian Debian Linux - [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild) - [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild) - [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild) - [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild) - [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2025-39718 and fix it if it is affected. What it is: CVE-2025-39718 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 5 Sep 2025. 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-2025-39718 in the wild and no public exploit code. Affected product: Debian Debian 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-2025-39718/ (Markdown: https://insights.sbomify.com/CVE-2025-39718/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39718 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39718 - OSV: https://osv.dev/vulnerability/CVE-2025-39718 --- From sbomify Insights: https://insights.sbomify.com/CVE-2025-39718/ Summaries are generated and may contain mistakes; the official description above is the record.