# CVE-2026-74582: packet: use consistent hard_header_len in non-ring send paths > A race condition in the Linux kernel packet socket implementation allows out-of-bounds writes, potentially leading to code execution or privilege escalation. - **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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:** 21 Aug 2026 - **Updated:** 16 Oct 2026 - **Also known as:** AZL-96995, BELL-CVE-2026-74582, DEBIAN-CVE-2026-74582, GHSA-6g47-hqw2-hv2r, RHSA-2026:63537, UBUNTU-CVE-2026-74582 ## What is CVE-2026-74582? CVE-2026-74582 is a high-severity vulnerability in Linux, published on 21 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: packet: use consistent hard_header_len in non-ring send paths packet_snd() reads dev->hard_header_len multiple times while allocating and constructing an skb. Device reconfiguration can change this value concurrently, for example through bonding device type changes. For SOCK_RAW, packet_snd() can save a larger value in reserve and later allocate headroom using a smaller value. Moving skb->data back by reserve then places it before skb->head, and the following copy from userspace can attempt an out-of-bounds write. packet_sendmsg_spkt() has the same issue because it calculates its reservation and header offset from separate reads before dropping the RCU read lock to allocate the skb. Add LL_RESERVED_SPACE_EX() for callers that already saved a header length. Read hard_header_len once in packet_snd() and use it for allocation and construction. In packet_sendmsg_spkt(), preserve the allocation-time value through the device lookup retry. The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here. ## Which versions are affected by CVE-2026-74582? | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `bpftool` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `bpftool-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-abi-stablelists` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-core` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-core` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-devel` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-modules` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-modules-extra` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debuginfo-common-ppc64le` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debuginfo-common-x86_64` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-devel` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-doc` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-modules` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-modules-extra` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-tools` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-tools-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-tools-libs` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `perf` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `perf-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `python3-perf` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `python3-perf-debuginfo` | Red Hat:rhel_e4s:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `bpftool` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `bpftool-debuginfo` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-abi-stablelists` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-core` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-core` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-debuginfo` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-devel` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-modules` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debug-modules-extra` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debuginfo` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-debuginfo-common-x86_64` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-devel` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | | `kernel-doc` | Red Hat:rhel_tus:8.8::baseos | All versions | 0:4.18.0-477.165.1.el8_8 | ## How do I fix CVE-2026-74582? Apply the vendor's patch. ## Is CVE-2026-74582 being exploited? There is no known exploitation of CVE-2026-74582 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-74582 and fix it if it is affected. What it is: CVE-2026-74582 is a high-severity vulnerability in Linux, published on 21 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-2026-74582 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-2026-74582/ (Markdown: https://insights.sbomify.com/CVE-2026-74582/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74582 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74582 - OSV: https://osv.dev/vulnerability/CVE-2026-74582 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-74582/ Summaries are generated and may contain mistakes; the official description above is the record.