{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21984 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21984 is a high-severity vulnerability in Linux kernel, published on 1 Apr 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-2025-21984 and fix it if it is affected.\n\nWhat it is: CVE-2025-21984 is a high-severity vulnerability in Linux kernel, published on 1 Apr 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-2025-21984 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-2025-21984/ (Markdown: https://insights.sbomify.com/CVE-2025-21984/index.md)","id":"CVE-2025-21984","markdown":"https://insights.sbomify.com/CVE-2025-21984/index.md","name":"CVE-2025-21984","record":{"aliases":["BELL-CVE-2025-21984","DEBIAN-CVE-2025-21984","GHSA-mw8g-4mvm-gj4f","ROOT-OS-UBUNTU-2404-CVE-2025-21984","UBUNTU-CVE-2025-21984"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A race condition in the Linux kernel's userfaultfd_move function can cause a kernel BUG and system crash when handling swap cache entries.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"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":[{"id":"CWE-362","name":"Concurrent Execution using Shared Resource with Improper Synchronization"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix kernel BUG when userfaultfd_move encounters swapcache\n\nuserfaultfd_move() checks whether the PTE entry is present or a\nswap entry.\n\n- If the PTE entry is present, move_present_pte() handles folio\n  migration by setting:\n\n  src_folio-\u003eindex = linear_page_index(dst_vma, dst_addr);\n\n- If the PTE entry is a swap entry, move_swap_pte() simply copies\n  the PTE to the new dst_addr.\n\nThis approach is incorrect because, even if the PTE is a swap entry,\nit can still reference a folio that remains in the swap cache.\n\nThis creates a race window between steps 2 and 4.\n 1. add_to_swap: The folio is added to the swapcache.\n 2. try_to_unmap: PTEs are converted to swap entries.\n 3. pageout: The folio is written back.\n 4. Swapcache is cleared.\nIf userfaultfd_move() occurs in the window between steps 2 and 4,\nafter the swap PTE has been moved to the destination, accessing the\ndestination triggers do_swap_page(), which may locate the folio in\nthe swapcache. However, since the folio's index has not been updated\nto match the destination VMA, do_swap_page() will detect a mismatch.\n\nThis can result in two critical issues depending on the system\nconfiguration.\n\nIf KSM is disabled, both small and large folios can trigger a BUG\nduring the add_rmap operation due to:\n\n page_pgoff(folio, page) != linear_page_index(vma, address)\n\n[   13.336953] page: refcount:6 mapcount:1 mapping:00000000f43db19c index:0xffffaf150 pfn:0x4667c\n[   13.337520] head: order:2 mapcount:1 entire_mapcount:0 nr_pages_mapped:1 pincount:0\n[   13.337716] memcg:ffff00000405f000\n[   13.337849] anon flags: 0x3fffc0000020459(locked|uptodate|dirty|owner_priv_1|head|swapbacked|node=0|zone=0|lastcpupid=0xffff)\n[   13.338630] raw: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361\n[   13.338831] raw: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000\n[   13.339031] head: 03fffc0000020459 ffff80008507b538 ffff80008507b538 ffff000006260361\n[   13.339204] head: 0000000ffffaf150 0000000000004000 0000000600000000 ffff00000405f000\n[   13.339375] head: 03fffc0000000202 fffffdffc0199f01 ffffffff00000000 0000000000000001\n[   13.339546] head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000\n[   13.339736] page dumped because: VM_BUG_ON_PAGE(page_pgoff(folio, page) != linear_page_index(vma, address))\n[   13.340190] ------------[ cut here ]------------\n[   13.340316] kernel BUG at mm/rmap.c:1380!\n[   13.340683] Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP\n[   13.340969] Modules linked in:\n[   13.341257] CPU: 1 UID: 0 PID: 107 Comm: a.out Not tainted 6.14.0-rc3-gcf42737e247a-dirty #299\n[   13.341470] Hardware name: linux,dummy-virt (DT)\n[   13.341671] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n[   13.341815] pc : __page_check_anon_rmap+0xa0/0xb0\n[   13.341920] lr : __page_check_anon_rmap+0xa0/0xb0\n[   13.342018] sp : ffff80008752bb20\n[   13.342093] x29: ffff80008752bb20 x28: fffffdffc0199f00 x27: 0000000000000001\n[   13.342404] x26: 0000000000000000 x25: 0000000000000001 x24: 0000000000000001\n[   13.342575] x23: 0000ffffaf0d0000 x22: 0000ffffaf0d0000 x21: fffffdffc0199f00\n[   13.342731] x20: fffffdffc0199f00 x19: ffff000006210700 x18: 00000000ffffffff\n[   13.342881] x17: 6c203d2120296567 x16: 6170202c6f696c6f x15: 662866666f67705f\n[   13.343033] x14: 6567617028454741 x13: 2929737365726464 x12: ffff800083728ab0\n[   13.343183] x11: ffff800082996bf8 x10: 0000000000000fd7 x9 : ffff80008011bc40\n[   13.343351] x8 : 0000000000017fe8 x7 : 00000000fffff000 x6 : ffff8000829eebf8\n[   13.343498] x5 : c0000000fffff000 x4 : 0000000000000000 x3 : 0000000000000000\n[   13.343645] x2 : 0000000000000000 x1 : ffff0000062db980 x0 : 000000000000005f\n[   13.343876] Call trace:\n[   13.344045]  __page_check_anon_rmap+0xa0/0xb0 (P)\n[   13.344234]  folio_add_anon_rmap_ptes+0x22c/0x320\n[   13.344333]  do_swap_page+0x1060/0x1400\n[   13.344417]  __handl\n---truncated---","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":"mm: fix kernel BUG when userfaultfd_move encounters swapcache","id":"CVE-2025-21984","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"race_condition","year":"2025"},"n_packages":0,"n_references":3,"next":{"headline":"drm/amd/display: Fix out-of-bound accesses","id":"CVE-2025-21985"},"packages":[],"prev":{"headline":"mm/slab/kvfree_rcu: Switch to WQ_MEM_RECLAIM wq","id":"CVE-2025-21983"},"products":["Linux"],"published":"2025-04-01","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":"partial"},"state":"PUBLISHED","updated":"2026-08-05","vendors":["Linux"]},"summary":"A race condition in the Linux kernel's userfaultfd_move function can cause a kernel BUG and system crash when handling swap cache entries.","url":"https://insights.sbomify.com/CVE-2025-21984/"}