{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-89661 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-89661 is an use after free 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-2026-89661 and fix it if it is affected.\n\nWhat it is: CVE-2026-89661 is an use after free 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-2026-89661 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-2026-89661/ (Markdown: https://insights.sbomify.com/CVE-2026-89661/index.md)","id":"CVE-2026-89661","markdown":"https://insights.sbomify.com/CVE-2026-89661/index.md","name":"CVE-2026-89661","record":{"aliases":["DEBIAN-CVE-2026-89661","GHSA-5jhw-w88m-cjf3","UBUNTU-CVE-2026-89661"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service","code_execution"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"high_privilege","summary":"A local administrator can trigger a use-after-free in the Linux kernel NFSD module by writing to a proc file after server shutdown, potentially causing a crash or code execution.","user_interaction":"not_required","vuln_class":"use_after_free"},"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\nNFSD: Prevent post-shutdown use-after-free in unlock_filesystem\n\nWriting a filesystem path to /proc/fs/nfsd/unlock_filesystem runs\nnfsd4_cancel_copy_by_sb() before nfsd_mutex is held and before the\nhandler confirms that nn-\u003enfsd_serv is set. Once nfsd has shut down,\nnfs4_state_destroy_net() has freed nn-\u003econf_id_hashtbl but left the\npointer intact, so the cancel helper iterates freed slab memory as an\narray of struct list_head and then dereferences a bogus nfs4_client\nwhen it takes clp-\u003easync_lock. A local administrator holding\nCAP_SYS_ADMIN can reach this use-after-free by stopping the server and\nthen writing to unlock_filesystem; KASAN reports a slab-use-after-free\nread in nfsd4_cancel_copy_by_sb().\n\nnfsd4_revoke_states() walks the same state tables and for that reason\nalready runs only under nfsd_mutex with nn-\u003enfsd_serv confirmed\npresent. Move the async COPY cancel into that protected section so\nevery NFSv4 state-table walker on this path observes a running server.\nAsync copies exist only while the server runs, so gating the cancel on\nnn-\u003enfsd_serv loses nothing.","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":"NFSD: Prevent post-shutdown use-after-free in unlock_filesystem","id":"CVE-2026-89661","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"use_after_free","year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"NFSD: Prevent lock owner use-after-free during client teardown","id":"CVE-2026-89662"},"packages":[],"prev":{"headline":"NFSD: Prevent client use-after-free during admin state revocation","id":"CVE-2026-89660"},"products":["Linux"],"published":"2026-09-11","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":"2026-10-19","vendors":["Linux"]},"summary":"A local administrator can trigger a use-after-free in the Linux kernel NFSD module by writing to a proc file after server shutdown, potentially causing a crash or code execution.","url":"https://insights.sbomify.com/CVE-2026-89661/"}