{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-46910 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2021-46910 is a high-severity vulnerability in Linux kernel, published on 27 Feb 2024. 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-2021-46910 and fix it if it is affected.\n\nWhat it is: CVE-2021-46910 is a high-severity vulnerability in Linux kernel, published on 27 Feb 2024. 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-2021-46910 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-2021-46910/ (Markdown: https://insights.sbomify.com/CVE-2021-46910/index.md)","id":"CVE-2021-46910","markdown":"https://insights.sbomify.com/CVE-2021-46910/index.md","name":"CVE-2021-46910","record":{"aliases":["DEBIAN-CVE-2021-46910","GHSA-gg7f-9mpf-7m5f","UBUNTU-CVE-2021-46910"],"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":"A kernel crash occurs during EFI boot on ARM systems with high CPU counts and debug kmap enabled, causing a denial of service.","user_interaction":"not_required","vuln_class":"null_dereference"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":7,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled\n\nThe debugging code for kmap_local() doubles the number of per-CPU fixmap\nslots allocated for kmap_local(), in order to use half of them as guard\nregions. This causes the fixmap region to grow downwards beyond the start\nof its reserved window if the supported number of CPUs is large, and collide\nwith the newly added virtual DT mapping right below it, which is obviously\nnot good.\n\nOne manifestation of this is EFI boot on a kernel built with NR_CPUS=32\nand CONFIG_DEBUG_KMAP_LOCAL=y, which may pass the FDT in highmem, resulting\nin block entries below the fixmap region that the fixmap code misidentifies\nas fixmap table entries, and subsequently tries to dereference using a\nphys-to-virt translation that is only valid for lowmem. This results in a\ncryptic splat such as the one below.\n\n  ftrace: allocating 45548 entries in 89 pages\n  8\u003c--- cut here ---\n  Unable to handle kernel paging request at virtual address fc6006f0\n  pgd = (ptrval)\n  [fc6006f0] *pgd=80000040207003, *pmd=00000000\n  Internal error: Oops: a06 [#1] SMP ARM\n  Modules linked in:\n  CPU: 0 PID: 0 Comm: swapper Not tainted 5.11.0+ #382\n  Hardware name: Generic DT based system\n  PC is at cpu_ca15_set_pte_ext+0x24/0x30\n  LR is at __set_fixmap+0xe4/0x118\n  pc : [\u003cc041ac9c\u003e]    lr : [\u003cc04189d8\u003e]    psr: 400000d3\n  sp : c1601ed8  ip : 00400000  fp : 00800000\n  r10: 0000071f  r9 : 00421000  r8 : 00c00000\n  r7 : 00c00000  r6 : 0000071f  r5 : ffade000  r4 : 4040171f\n  r3 : 00c00000  r2 : 4040171f  r1 : c041ac78  r0 : fc6006f0\n  Flags: nZcv  IRQs off  FIQs off  Mode SVC_32  ISA ARM  Segment none\n  Control: 30c5387d  Table: 40203000  DAC: 00000001\n  Process swapper (pid: 0, stack limit = 0x(ptrval))\n\nSo let's limit CONFIG_NR_CPUS to 16 when CONFIG_DEBUG_KMAP_LOCAL=y. Also,\nfix the BUILD_BUG_ON() check that was supposed to catch this, by checking\nwhether the region grows below the start address rather than above the end\naddress.","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":"ARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled","id":"CVE-2021-46910","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"null_dereference","year":"2021"},"n_packages":0,"n_references":2,"next":{"headline":"ch_ktls: Fix kernel panic","id":"CVE-2021-46911"},"packages":[],"prev":{"headline":"ARM: footbridge: fix PCI interrupt mapping","id":"CVE-2021-46909"},"products":["Linux"],"published":"2024-02-27","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":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-08-05","vendors":["Linux"]},"summary":"A kernel crash occurs during EFI boot on ARM systems with high CPU counts and debug kmap enabled, causing a denial of service.","url":"https://insights.sbomify.com/CVE-2021-46910/"}