{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-89966 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-89966 is a vulnerability in Linux, published on 16 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-2026-89966 and fix it if it is affected.\n\nWhat it is: CVE-2026-89966 is a vulnerability in Linux, published on 16 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-2026-89966 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-2026-89966/ (Markdown: https://insights.sbomify.com/CVE-2026-89966/index.md)","id":"CVE-2026-89966","markdown":"https://insights.sbomify.com/CVE-2026-89966/index.md","name":"CVE-2026-89966","record":{"aliases":["DEBIAN-CVE-2026-89966","GHSA-j92g-qm8v-9jw7","UBUNTU-CVE-2026-89966"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":true,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"An unprivileged local user can crash the Linux kernel by triggering a null pointer dereference during gigantic hugepage allocation on systems with specific CMA configurations.","user_interaction":"not_required","vuln_class":"null_dereference"},"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\nmm/hugetlb_cma: fix null nodemask dereference in hugetlb_cma_alloc_frozen_folio\n\nalloc_buddy_hugetlb_folio_with_mpol() can pass a NULL nodemask to\nalloc_fresh_hugetlb_folio() as a fallback to allocate from all nodes.  If\norder is gigantic, alloc_fresh_hugetlb_folio() propagates the NULL\nnodemask down to hugetlb_cma_alloc_frozen_folio() via\nalloc_gigantic_frozen_folio().\n\nAdditionally, hugetlb_cma_alloc_frozen_folio() previously attempted\nallocation on hugetlb_cma[nid] without verifying if nid is included in the\ncaller's nodemask.  Adding a node_isset(nid, *nodemask) check ensures the\ninitial preferred node allocation honors the memory policy / nodemask.\n\nHowever, hugetlb_cma_alloc_frozen_folio() dereferences the nodemask in\nnode_isset(nid, *nodemask) and for_each_node_mask(node, *nodemask),\nleading to a null pointer dereference kernel panic when nodemask is NULL.\n\nFix this by checking if nodemask is NULL in\nhugetlb_cma_alloc_frozen_folio() and defaulting it to\ncpuset_current_mems_allowed.  Enclose the allocation attempts within the\ncpuset seqcount retry loop so that if the cpuset changes concurrently\nduring allocation, the attempts are retried using the updated nodemask. \nThis ensures that the initial node check and fallback loop safely honor\nthe task's cpuset without violating cpuset constraints or causing NULL\npointer dereferences or unexpected allocation failures.\n\nFrom a userspace perspective, this bug allows an unprivileged user to\ncrash the kernel (trigger a panic) by requesting a gigantic hugepage\nallocation with MPOL_PREFERRED_MANY on a system where CMA is only\nconfigured on a subset of NUMA nodes.\n\nThis can be reproduced by booting a VM with two NUMA nodes, restricting\nCMA to Node 1 (e.g., hugetlb_cma=1:1G default_hugepagesz=1G hugepagesz=1G\nhugepages=0), and running a program that allocates a 1GB hugepage area\nwithout reserving, restricts allocation to Node 0 using mbind() with\nMPOL_PREFERRED_MANY, and triggers a page fault:\n\n  void *ptr = mmap(NULL, 1UL \u003c\u003c 30, PROT_READ | PROT_WRITE,\n                   MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB |\n                   MAP_HUGE_1GB | MAP_NORESERVE, -1, 0);\n  unsigned long nodemask = 1; /* Node 0 */\n  mbind(ptr, 1UL \u003c\u003c 30, MPOL_PREFERRED_MANY, \u0026nodemask,\n        sizeof(nodemask) * 8, 0);\n  memset(ptr, 0, 1UL \u003c\u003c 30); /* Trigger fault */\n\nThis results in a NULL pointer dereference:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000000\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  Oops: Oops: 0000 [#1] SMP NOPTI\n  RIP: 0010:hugetlb_cma_alloc_frozen_folio+0x75/0x120\n  Call Trace:\n   \u003cTASK\u003e\n   only_alloc_fresh_hugetlb_folio.isra.0+0x2c/0x160\n   alloc_surplus_hugetlb_folio+0x6d/0x100\n   alloc_hugetlb_folio+0x3c5/0x660\n   hugetlb_no_page+0x3d9/0x650","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/hugetlb_cma: fix null nodemask dereference in hugetlb_cma_alloc_frozen_folio","id":"CVE-2026-89966","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"null_dereference","year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"mm/migrate_device: avoid out-of-bounds writes for compound folios","id":"CVE-2026-89967"},"packages":[],"prev":{"headline":"nvdimm/btt: reject an arena whose nfree is below the lane count","id":"CVE-2026-89965"},"products":["Linux"],"published":"2026-09-16","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":"An unprivileged local user can crash the Linux kernel by triggering a null pointer dereference during gigantic hugepage allocation on systems with specific CMA configurations.","url":"https://insights.sbomify.com/CVE-2026-89966/"}