{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-81000 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-81000 is a high-severity vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-81000 and fix it if it is affected.\n\nWhat it is: CVE-2026-81000 is a high-severity vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-81000 in the wild and no public exploit code.\n\nAffected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. 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.\n2. 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.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-81000/ (Markdown: https://insights.sbomify.com/CVE-2026-81000/index.md)","id":"CVE-2026-81000","markdown":"https://insights.sbomify.com/CVE-2026-81000/index.md","name":"CVE-2026-81000","record":{"aliases":["AZL-100232","BELL-CVE-2026-81000","DEBIAN-CVE-2026-81000","GHSA-32hf-vhcc-85c2","UBUNTU-CVE-2026-81000"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["code_execution","denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"An integer underflow in the Linux kernel TUN driver allows memory corruption, potentially leading to code execution or denial of service.","user_interaction":"not_required","vuln_class":"integer_overflow"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":7.8,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tun: bound receive headroom\n\ntun_get_user() uses tun-\u003ealign both as skb headroom and when choosing how\nmuch packet data to keep linear. OVS can propagate an oversized headroom\nrequest from another port to TUN or TAP.\n\nWhen align is larger than the usable space in a one-page skb head,\nSKB_MAX_HEAD(align) underflows and the result becomes negative when stored\nin good_linear. That value later wraps when assigned to the size_t linear\nvariable, and tun_alloc_skb() can place skb-\u003edata outside the allocated\nhead.\n\nBound the headroom stored by TUN to the one-page skb-head budget and the\nlargest non-sentinel 16-bit skb header offset. Leave one linear byte for\nraw TUN and a complete Ethernet header for TAP, including NET_IP_ALIGN.\n\nAlso pull the raw-TUN protocol byte and the TAP Ethernet header before\naccessing them, so these checks remain safe for nonlinear skbs supplied by\nother allocation paths.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":"2026-09-18","github_poc":3,"max_poc_stars":0,"metasploit":0,"nuclei":0,"refs":[{"date":"2026-09-18T10:08:39Z","kind":"github_poc","ref":"https://github.com/suominen/tunderflow","stars":0,"title":"Tracking TUNderflow (CVE-2026-81000), the Linux kernel TUN/TAP receive-headroom underflow"},{"date":"2026-09-19T16:25:07Z","kind":"github_poc","ref":"https://github.com/0xredash/CVE-2026-81000","stars":0,"title":"CVE-2026-81000"},{"date":"2026-09-21T02:18:26Z","kind":"github_poc","ref":"https://github.com/HORKimhab/CVE-2026-81000","stars":0,"title":"CVE-2026-81000"}],"tier":"poc_unverified"},"has_fix":true,"headline":"net: tun: bound receive headroom","id":"CVE-2026-81000","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"integer_overflow","year":"2026"},"n_packages":0,"n_references":8,"next":{"headline":"slip: fix use-after-free in sl_sync()","id":"CVE-2026-81001"},"packages":[],"prev":{"headline":"net: dsa: realtek: use gpiod_set_value_cansleep for reset GPIO","id":"CVE-2026-80999"},"products":["Linux"],"published":"2026-09-11","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"},{"class":"open","licence":"CC0","name":"PoC-in-GitHub"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-19","vendors":["Linux"]},"summary":"An integer underflow in the Linux kernel TUN driver allows memory corruption, potentially leading to code execution or denial of service.","url":"https://insights.sbomify.com/CVE-2026-81000/"}