{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21840 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21840 is a medium-severity vulnerability in Linux kernel, published on 7 Mar 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-2025-21840 and fix it if it is affected.\n\nWhat it is: CVE-2025-21840 is a medium-severity vulnerability in Linux kernel, published on 7 Mar 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-2025-21840 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-2025-21840/ (Markdown: https://insights.sbomify.com/CVE-2025-21840/index.md)","id":"CVE-2025-21840","markdown":"https://insights.sbomify.com/CVE-2025-21840/index.md","name":"CVE-2025-21840","record":{"aliases":["BELL-CVE-2025-21840","GHSA-pcf3-xr6w-mj6g","UBUNTU-CVE-2025-21840"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel thermal","requires_auth":"low_privilege","summary":"A kernel thermal netlink header change caused userspace segmentation faults in tools like intel-lpmd, leading to 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":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nthermal/netlink: Prevent userspace segmentation fault by adjusting UAPI header\n\nThe intel-lpmd tool [1], which uses the THERMAL_GENL_ATTR_CPU_CAPABILITY\nattribute to receive HFI events from kernel space, encounters a\nsegmentation fault after commit 1773572863c4 (\"thermal: netlink: Add the\ncommands and the events for the thresholds\").\n\nThe issue arises because the THERMAL_GENL_ATTR_CPU_CAPABILITY raw value\nwas changed while intel_lpmd still uses the old value.\n\nAlthough intel_lpmd can be updated to check the THERMAL_GENL_VERSION and\nuse the appropriate THERMAL_GENL_ATTR_CPU_CAPABILITY value, the commit\nitself is questionable.\n\nThe commit introduced a new element in the middle of enum thermal_genl_attr,\nwhich affects many existing attributes and introduces potential risks\nand unnecessary maintenance burdens for userspace thermal netlink event\nusers.\n\nSolve the issue by moving the newly introduced\nTHERMAL_GENL_ATTR_TZ_PREV_TEMP attribute to the end of the\nenum thermal_genl_attr. This ensures that all existing thermal generic\nnetlink attributes remain unaffected.\n\n[ rjw: Subject edits ]","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":"thermal/netlink: Prevent userspace segmentation fault by adjusting UAPI header","id":"CVE-2025-21840","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"null_dereference","year":"2025"},"n_packages":0,"n_references":2,"next":{"headline":"cpufreq/amd-pstate: Fix cpufreq_policy ref counting","id":"CVE-2025-21841"},"packages":[],"prev":{"headline":"KVM: x86: Load DR6 with guest value only before entering .vcpu_run() loop","id":"CVE-2025-21839"},"products":["Linux"],"published":"2025-03-07","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":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A kernel thermal netlink header change caused userspace segmentation faults in tools like intel-lpmd, leading to denial of service.","url":"https://insights.sbomify.com/CVE-2025-21840/"}