{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-63836 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-63836 is a vulnerability in Linux, published on 19 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-63836 and fix it if it is affected.\n\nWhat it is: CVE-2026-63836 is a vulnerability in Linux, published on 19 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-63836 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-2026-63836/ (Markdown: https://insights.sbomify.com/CVE-2026-63836/index.md)","id":"CVE-2026-63836","markdown":"https://insights.sbomify.com/CVE-2026-63836/index.md","name":"CVE-2026-63836","record":{"aliases":["BELL-CVE-2026-63836","DEBIAN-CVE-2026-63836","GHSA-f3pj-q27g-923q","ROOT-OS-DEBIAN-11-CVE-2026-63836","ROOT-OS-UBUNTU-2204-CVE-2026-63836","UBUNTU-CVE-2026-63836"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"yes","non_default_config":false,"product_category":"Linux kernel","requires_auth":"none","summary":"An integer overflow in the batman-adv tp_meter module causes a divide-by-zero error, leading to a kernel crash and denial of service.","user_interaction":"not_required","vuln_class":"integer_overflow"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":null,"severity":null,"source":null,"vector":null,"version":null},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: tp_meter: avoid divide-by-zero for dec_cwnd\n\nThe cwnd is always MSS \u003c= cwnd \u003c= 0x20000000. But the calculation in\nbatadv_tp_update_cwnd() assumes unsigned 32 bit arithmetics.\n\n    ((mss * 8) ** 2) / (cwnd * 8)\n\nIn case cwnd is actually 0x20000000, it will be shifted by 3 bit to the\nleft end up at 0x100000000 or U32_MAX + 1. It will therefore wrap around\nand be 0 - resulting in:\n\n    ((mss * 8) ** 2) / 0\n\nThis is of course invalid and cannot be calculated. The calculation should\nmust be simplified to avoid this overflow:\n\n   (mss ** 2) * 8 / cwnd\n\nIt will keep the precision enhancement from the scaling (by 8) but avoid\nthe overflow in the divisor.\n\nIn theory, there could still be an overflow in the dividend. It is at the\nmoment fixed to BATADV_TP_PLEN in batadv_tp_recv_ack() - so it is not an\nimminent problem. But allowing it to use the whole u32 bit range, would\nmean that it can still use up to 67 bits. To keep this calculation safe for\n32 bit arithmetic, mss must never use more than floor((32 - 3) / 2) bits -\nor in other words: must never be larger than 16383.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"batman-adv: tp_meter: avoid divide-by-zero for dec_cwnd","id":"CVE-2026-63836","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":"net: ena: PHC: Check return code before setting timestamp output","id":"CVE-2026-63837"},"packages":[],"prev":{"headline":"batman-adv: v: prevent OGM aggregation on disabled hardif","id":"CVE-2026-63835"},"products":["Linux"],"published":"2026-07-19","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-08-17","vendors":["Linux"]},"summary":"An integer overflow in the batman-adv tp_meter module causes a divide-by-zero error, leading to a kernel crash and denial of service.","url":"https://insights.sbomify.com/CVE-2026-63836/"}