# CVE-2026-80844: xfrm: ah6: validate routing header segments_left > A missing validation in the Linux kernel's AH6 implementation allows remote attackers to trigger an out-of-bounds memory access via crafted IPv6 packets. - **Severity:** Not scored - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 4 Sep 2026 - **Updated:** 19 Oct 2026 - **Also known as:** AZL-99411, BELL-CVE-2026-80844, DEBIAN-CVE-2026-80844, GHSA-jv4j-682x-84w7, RHSA-2026:74974, UBUNTU-CVE-2026-80844 ## What is CVE-2026-80844? CVE-2026-80844 is a memory corruption vulnerability in Linux, published on 4 Sep 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: xfrm: ah6: validate routing header segments_left AH6 rearranges routing-header addresses before computing or verifying the ICV. ipv6_rearrange_rthdr() assumes that segments_left is not larger than the number of addresses described by the routing header's hdrlen field. That assumption does not hold for raw IPv6 HDRINCL packets. A packet with hdrlen equal to 2 describes one address, but can carry an arbitrary segments_left value. With segments_left equal to 255, the function moves its address pointer 4,064 bytes backwards and passes a 4,064-byte length to memmove(), resulting in an out-of-bounds access. Validate the invariant locally before modifying the routing header or performing any address-pointer arithmetic, and propagate malformed-header errors to the existing AH6 input and output error paths. ## Which versions are affected by CVE-2026-80844? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `kernel` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug-debuginfo` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug-devel` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug-devel-matched` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug-modules` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug-modules-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debug-modules-extra` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-debuginfo` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-devel` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-devel-matched` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-modules` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-modules-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-64k-modules-extra` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-abi-stablelists` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug-debuginfo` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug-devel` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug-devel-matched` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug-modules` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug-modules-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debug-modules-extra` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debuginfo` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-debuginfo-common-aarch64` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-devel` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-devel-matched` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-doc` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-modules` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-modules-core` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-modules-extra` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-modules-extra-matched` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-tools` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-tools-debuginfo` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-tools-libs` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | | `kernel-tools-libs-devel` | Red Hat:enterprise_linux_nvidia:10::el10 | All versions | 0:6.12.0-259.28.el10nv | ## How do I fix CVE-2026-80844? Apply the vendor's patch. ## Is CVE-2026-80844 being exploited? There is no known exploitation of CVE-2026-80844 in the wild and no public exploit code. Public exploit code: - Tracking DirtyAH6 (CVE-2026-80844), the Linux kernel IPv6 AH routing-header out-of-bounds write (github_poc): https://github.com/suominen/dirtyah6 - CVE-2026-80844 (github_poc): https://github.com/0xredash/CVE-2026-80844 - CVE-2026-80844, DirtyAH6 (github_poc): https://github.com/HORKimhab/CVE-2026-80844 ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-80844 and fix it if it is affected. What it is: CVE-2026-80844 is a memory corruption vulnerability in Linux, published on 4 Sep 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-2026-80844 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-2026-80844/ (Markdown: https://insights.sbomify.com/CVE-2026-80844/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80844 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80844 - OSV: https://osv.dev/vulnerability/CVE-2026-80844 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-80844/ Summaries are generated and may contain mistakes; the official description above is the record.