{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21731 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21731 is a high-severity use after free vulnerability in Linux kernel, published on 27 Feb 2025. 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-2025-21731 and fix it if it is affected.\n\nWhat it is: CVE-2025-21731 is a high-severity use after free vulnerability in Linux kernel, published on 27 Feb 2025. 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-2025-21731 in the wild and no public exploit code.\n\nAffected product: Linux kernel. 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-2025-21731/ (Markdown: https://insights.sbomify.com/CVE-2025-21731/index.md)","id":"CVE-2025-21731","markdown":"https://insights.sbomify.com/CVE-2025-21731/index.md","name":"CVE-2025-21731","record":{"aliases":["AZL-59043","BELL-CVE-2025-21731","DEBIAN-CVE-2025-21731","GHSA-2qfv-5w3v-jvfv","ROOT-OS-UBUNTU-2404-CVE-2025-21731","UBUNTU-CVE-2025-21731"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["code_execution","privilege_escalation"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A use-after-free vulnerability in the Linux kernel's NBD driver allows local attackers to execute arbitrary code or escalate privileges via a race condition during disconnect and reconnect operations.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":7.8,"severity":"high","source":"cisa-adp","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: don't allow reconnect after disconnect\n\nFollowing process can cause nbd_config UAF:\n\n1) grab nbd_config temporarily;\n\n2) nbd_genl_disconnect() flush all recv_work() and release the\ninitial reference:\n\n  nbd_genl_disconnect\n   nbd_disconnect_and_put\n    nbd_disconnect\n     flush_workqueue(nbd-\u003erecv_workq)\n    if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...))\n     nbd_config_put\n     -\u003e due to step 1), reference is still not zero\n\n3) nbd_genl_reconfigure() queue recv_work() again;\n\n  nbd_genl_reconfigure\n   config = nbd_get_config_unlocked(nbd)\n   if (!config)\n   -\u003e succeed\n   if (!test_bit(NBD_RT_BOUND, ...))\n   -\u003e succeed\n   nbd_reconnect_socket\n    queue_work(nbd-\u003erecv_workq, \u0026args-\u003ework)\n\n4) step 1) release the reference;\n\n5) Finially, recv_work() will trigger UAF:\n\n  recv_work\n   nbd_config_put(nbd)\n   -\u003e nbd_config is freed\n   atomic_dec(\u0026config-\u003erecv_threads)\n   -\u003e UAF\n\nFix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so\nthat nbd_genl_reconfigure() will fail.","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":"nbd: don't allow reconnect after disconnect","id":"CVE-2025-21731","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"use_after_free","year":"2025"},"n_packages":0,"n_references":8,"next":{"headline":"RDMA/mlx5: Fix a race for an ODP MR which leads to CQE with error","id":"CVE-2025-21732"},"packages":[],"prev":{"headline":"wifi: rtw89: avoid to init mgnt_entry list twice when WoWLAN failed","id":"CVE-2025-21730"},"products":["Linux"],"published":"2025-02-27","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-15","vendors":["Linux"]},"summary":"A use-after-free vulnerability in the Linux kernel's NBD driver allows local attackers to execute arbitrary code or escalate privileges via a race condition during disconnect and reconnect operations.","url":"https://insights.sbomify.com/CVE-2025-21731/"}