{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21806 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21806 is a medium-severity denial of service 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-2025-21806 and fix it if it is affected.\n\nWhat it is: CVE-2025-21806 is a medium-severity denial of service 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-2025-21806 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-2025-21806/ (Markdown: https://insights.sbomify.com/CVE-2025-21806/index.md)","id":"CVE-2025-21806","markdown":"https://insights.sbomify.com/CVE-2025-21806/index.md","name":"CVE-2025-21806","record":{"aliases":["BELL-CVE-2025-21806","DEBIAN-CVE-2025-21806","GHSA-mq5p-7q76-276p","ROOT-OS-UBUNTU-2404-CVE-2025-21806","UBUNTU-CVE-2025-21806"],"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 local administrator can cause a kernel warning and potential instability by setting net.core.dev_weight to zero, leading to a denial of service.","user_interaction":"not_required","vuln_class":"denial_of_service"},"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\nnet: let net.core.dev_weight always be non-zero\n\nThe following problem was encountered during stability test:\n\n(NULL net_device): NAPI poll function process_backlog+0x0/0x530 \\\n\treturned 1, exceeding its budget of 0.\n------------[ cut here ]------------\nlist_add double add: new=ffff88905f746f48, prev=ffff88905f746f48, \\\n\tnext=ffff88905f746e40.\nWARNING: CPU: 18 PID: 5462 at lib/list_debug.c:35 \\\n\t__list_add_valid_or_report+0xf3/0x130\nCPU: 18 UID: 0 PID: 5462 Comm: ping Kdump: loaded Not tainted 6.13.0-rc7+\nRIP: 0010:__list_add_valid_or_report+0xf3/0x130\nCall Trace:\n? __warn+0xcd/0x250\n? __list_add_valid_or_report+0xf3/0x130\nenqueue_to_backlog+0x923/0x1070\nnetif_rx_internal+0x92/0x2b0\n__netif_rx+0x15/0x170\nloopback_xmit+0x2ef/0x450\ndev_hard_start_xmit+0x103/0x490\n__dev_queue_xmit+0xeac/0x1950\nip_finish_output2+0x6cc/0x1620\nip_output+0x161/0x270\nip_push_pending_frames+0x155/0x1a0\nraw_sendmsg+0xe13/0x1550\n__sys_sendto+0x3bf/0x4e0\n__x64_sys_sendto+0xdc/0x1b0\ndo_syscall_64+0x5b/0x170\nentry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nThe reproduction command is as follows:\n  sysctl -w net.core.dev_weight=0\n  ping 127.0.0.1\n\nThis is because when the napi's weight is set to 0, process_backlog() may\nreturn 0 and clear the NAPI_STATE_SCHED bit of napi-\u003estate, causing this\nnapi to be re-polled in net_rx_action() until __do_softirq() times out.\nSince the NAPI_STATE_SCHED bit has been cleared, napi_schedule_rps() can\nbe retriggered in enqueue_to_backlog(), causing this issue.\n\nMaking the napi's weight always non-zero solves this problem.\n\nTriggering this issue requires system-wide admin (setting is\nnot namespaced).","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":"net: let net.core.dev_weight always be non-zero","id":"CVE-2025-21806","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"denial_of_service","year":"2025"},"n_packages":0,"n_references":8,"next":{"headline":"block: fix queue freeze vs limits lock order in sysfs store methods","id":"CVE-2025-21807"},"packages":[],"prev":{"headline":"RDMA/rtrs: Add missing deinit() call","id":"CVE-2025-21805"},"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":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-10-15","vendors":["Linux"]},"summary":"A local administrator can cause a kernel warning and potential instability by setting net.core.dev_weight to zero, leading to a denial of service.","url":"https://insights.sbomify.com/CVE-2025-21806/"}