# CVE-2026-74581: net: ipv6: clear suppressed fib6 rule result > A use-after-free in the Linux kernel IPv6 routing code allows attackers to cause a denial of service or potentially execute code via crafted network traffic. - **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:** 21 Aug 2026 - **Updated:** 16 Oct 2026 - **Also known as:** AZL-97001, BELL-CVE-2026-74581, DEBIAN-CVE-2026-74581, GHSA-7ph7-58w3-w755, RHSA-2026:59994, RHSA-2026:60437, RHSA-2026:60438, RHSA-2026:60485, UBUNTU-CVE-2026-74581 ## What is CVE-2026-74581? CVE-2026-74581 is a critical use after free vulnerability in Linux, published on 21 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: ipv6: clear suppressed fib6 rule result fib6_rule_suppress() drops a suppressed route with ip6_rt_put_flags(), but leaves res->rt6 pointing at the released rt6_info. If no later rule supplies a replacement, fib6_rule_lookup() still sees res.rt6 and returns that stale dst to its caller. A suppressing rule can therefore leak a released route back to rt6_lookup(), and the next put hits rcuref_put_slowpath() from dst_release(). Clear res->rt6 when suppressing the route so suppressed lookups fall through to the null dst instead of reusing the released one. ## Which versions are affected by CVE-2026-74581? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `bpftool` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `bpftool-debuginfo` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-abi-stablelists` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-core` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debug` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debug-core` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debug-debuginfo` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debug-devel` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debug-modules` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debug-modules-extra` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debuginfo` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-debuginfo-common-x86_64` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-devel` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-doc` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-modules` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-modules-extra` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-tools` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-tools-debuginfo` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `kernel-tools-libs` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `perf` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `perf-debuginfo` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `python3-perf` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `python3-perf-debuginfo` | Red Hat:rhel_aus:8.4::baseos | All versions | 0:4.18.0-305.202.1.el8_4 | | `bpftool` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `bpftool-debuginfo` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-abi-stablelists` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-core` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debug` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debug-core` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debug-debuginfo` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debug-devel` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debug-modules` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debug-modules-extra` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debuginfo` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-debuginfo-common-x86_64` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-devel` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-doc` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | | `kernel-modules` | Red Hat:rhel_aus:8.6::baseos | All versions | 0:4.18.0-372.209.1.el8_6 | ## How do I fix CVE-2026-74581? Apply the vendor's patch. ## Is CVE-2026-74581 being exploited? There is no known exploitation of CVE-2026-74581 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-74581 and fix it if it is affected. What it is: CVE-2026-74581 is a critical use after free vulnerability in Linux, published on 21 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-2026-74581 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-2026-74581/ (Markdown: https://insights.sbomify.com/CVE-2026-74581/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74581 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74581 - OSV: https://osv.dev/vulnerability/CVE-2026-74581 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-74581/ Summaries are generated and may contain mistakes; the official description above is the record.