# CVE-2026-74480: net: bridge: stop fast-leave after deleting a port group > A use-after-free in the Linux kernel bridge multicast code allows attackers to cause a denial of service or potentially execute code when fast-leave is enabled. - **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/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:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 15 Aug 2026 - **Updated:** 16 Oct 2026 - **Also known as:** ALSA-2026:66355, AZL-96423, BELL-CVE-2026-74480, DEBIAN-CVE-2026-74480, GHSA-98rv-7h6m-5q72, RHSA-2026:61973, RHSA-2026:62345, RHSA-2026:62372, RHSA-2026:63538, RHSA-2026:63539, RHSA-2026:66355, RLSA-2026:66355, UBUNTU-CVE-2026-74480 ## What is CVE-2026-74480? CVE-2026-74480 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: net: bridge: stop fast-leave after deleting a port group br_multicast_leave_group() iterates mp->ports with pp = &p->next in its fast-leave path. After br_multicast_del_pg() removes p, continuing the loop advances pp through the deleted entry. If multicast-to-unicast was enabled, the bridge can hold multiple port groups for the same port and group with different source MAC addresses. Once multicast-to-unicast is disabled, br_port_group_equal() matches those entries by port only. A fast leave can then delete one entry and continue from its stale next pointer, leaving mp->ports pointing at a deleted port group. Fast leave only needs to remove one matching port group. Break after br_multicast_del_pg() so the loop stops before dereferencing the removed entry. ## Which versions are affected by CVE-2026-74480? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `kernel` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-debug` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-debug-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-debug-devel` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-debug-devel-matched` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-debug-modules` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-debug-modules-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-debug-modules-extra` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-devel` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-devel-matched` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-modules` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-modules-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-64k-modules-extra` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-abi-stablelists` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-cross-headers` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug-devel` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug-devel-matched` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug-modules` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug-modules-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug-modules-extra` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-debug-uki-virt` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-devel` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-devel-matched` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-doc` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-headers` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-modules` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-modules-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-modules-extra` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-modules-extra-matched` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-rt` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-rt-64k` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-rt-64k-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-rt-64k-debug` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-rt-64k-debug-core` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | | `kernel-rt-64k-debug-devel` | AlmaLinux:10 | All versions | 6.12.0-211.54.1.el10_2 | ## How do I fix CVE-2026-74480? Apply the vendor's patch. ## Is CVE-2026-74480 being exploited? There is no known exploitation of CVE-2026-74480 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-74480 and fix it if it is affected. What it is: CVE-2026-74480 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-74480 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-2026-74480/ (Markdown: https://insights.sbomify.com/CVE-2026-74480/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74480 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74480 - OSV: https://osv.dev/vulnerability/CVE-2026-74480 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-74480/ Summaries are generated and may contain mistakes; the official description above is the record.