{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-46981 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2021-46981 is a medium-severity vulnerability in Linux kernel, published on 28 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-2021-46981 and fix it if it is affected.\n\nWhat it is: CVE-2021-46981 is a medium-severity vulnerability in Linux kernel, published on 28 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-2021-46981 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-2021-46981/ (Markdown: https://insights.sbomify.com/CVE-2021-46981/index.md)","id":"CVE-2021-46981","markdown":"https://insights.sbomify.com/CVE-2021-46981/index.md","name":"CVE-2021-46981","record":{"aliases":["DEBIAN-CVE-2021-46981","GHSA-xgg4-mwfh-3vj5","UBUNTU-CVE-2021-46981"],"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 local attacker can trigger a kernel crash by disconnecting an NBD device, 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":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":[{"id":"CWE-476","name":"NULL Pointer Dereference"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: Fix NULL pointer in flush_workqueue\n\nOpen /dev/nbdX first, the config_refs will be 1 and\nthe pointers in nbd_device are still null. Disconnect\n/dev/nbdX, then reference a null recv_workq. The\nprotection by config_refs in nbd_genl_disconnect is useless.\n\n[  656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020\n[  656.368943] #PF: supervisor write access in kernel mode\n[  656.369844] #PF: error_code(0x0002) - not-present page\n[  656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0\n[  656.371693] Oops: 0002 [#1] SMP\n[  656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1\n[  656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014\n[  656.375904] RIP: 0010:mutex_lock+0x29/0x60\n[  656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 \u003cf0\u003e 48 0f b1 55 d\n[  656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246\n[  656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[  656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020\n[  656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318\n[  656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40\n[  656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00\n[  656.382166] FS:  00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000\n[  656.382806] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[  656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0\n[  656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n[  656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n[  656.384927] Call Trace:\n[  656.385111]  flush_workqueue+0x92/0x6c0\n[  656.385395]  nbd_disconnect_and_put+0x81/0xd0\n[  656.385716]  nbd_genl_disconnect+0x125/0x2a0\n[  656.386034]  genl_family_rcv_msg_doit.isra.0+0x102/0x1b0\n[  656.386422]  genl_rcv_msg+0xfc/0x2b0\n[  656.386685]  ? nbd_ioctl+0x490/0x490\n[  656.386954]  ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0\n[  656.387354]  netlink_rcv_skb+0x62/0x180\n[  656.387638]  genl_rcv+0x34/0x60\n[  656.387874]  netlink_unicast+0x26d/0x590\n[  656.388162]  netlink_sendmsg+0x398/0x6c0\n[  656.388451]  ? netlink_rcv_skb+0x180/0x180\n[  656.388750]  ____sys_sendmsg+0x1da/0x320\n[  656.389038]  ? ____sys_recvmsg+0x130/0x220\n[  656.389334]  ___sys_sendmsg+0x8e/0xf0\n[  656.389605]  ? ___sys_recvmsg+0xa2/0xf0\n[  656.389889]  ? handle_mm_fault+0x1671/0x21d0\n[  656.390201]  __sys_sendmsg+0x6d/0xe0\n[  656.390464]  __x64_sys_sendmsg+0x23/0x30\n[  656.390751]  do_syscall_64+0x45/0x70\n[  656.391017]  entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\nTo fix it, just add if (nbd-\u003erecv_workq) to nbd_disconnect_and_put().","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":"nbd: Fix NULL pointer in flush_workqueue","id":"CVE-2021-46981","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":5,"next":{"headline":"f2fs: compress: fix race condition of overwrite vs truncate","id":"CVE-2021-46982"},"packages":[],"prev":{"headline":"usb: typec: ucsi: Retrieve all the PDOs instead of just the first 4","id":"CVE-2021-46980"},"products":["Linux"],"published":"2024-02-28","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":"2026-05-23","vendors":["Linux"]},"summary":"A local attacker can trigger a kernel crash by disconnecting an NBD device, causing a denial of service.","url":"https://insights.sbomify.com/CVE-2021-46981/"}