{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21721 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21721 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-2025-21721 and fix it if it is affected.\n\nWhat it is: CVE-2025-21721 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-2025-21721 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-2025-21721/ (Markdown: https://insights.sbomify.com/CVE-2025-21721/index.md)","id":"CVE-2025-21721","markdown":"https://insights.sbomify.com/CVE-2025-21721/index.md","name":"CVE-2025-21721","record":{"aliases":["BELL-CVE-2025-21721","DEBIAN-CVE-2025-21721","GHSA-6x53-8wjp-mwv4","ROOT-OS-UBUNTU-2404-CVE-2025-21721","UBUNTU-CVE-2025-21721"],"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 missing error check in the nilfs2 filesystem can cause a kernel crash via BUG_ON when directory rename operations encounter metadata errors.","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":[{"id":"CWE-617","name":"Reachable Assertion"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnilfs2: handle errors that nilfs_prepare_chunk() may return\n\nPatch series \"nilfs2: fix issues with rename operations\".\n\nThis series fixes BUG_ON check failures reported by syzbot around rename\noperations, and a minor behavioral issue where the mtime of a child\ndirectory changes when it is renamed instead of moved.\n\nThis patch (of 2):\n\nThe directory manipulation routines nilfs_set_link() and\nnilfs_delete_entry() rewrite the directory entry in the folio/page\npreviously read by nilfs_find_entry(), so error handling is omitted on the\nassumption that nilfs_prepare_chunk(), which prepares the buffer for\nrewriting, will always succeed for these.  And if an error is returned, it\ntriggers the legacy BUG_ON() checks in each routine.\n\nThis assumption is wrong, as proven by syzbot: the buffer layer called by\nnilfs_prepare_chunk() may call nilfs_get_block() if necessary, which may\nfail due to metadata corruption or other reasons.  This has been there all\nalong, but improved sanity checks and error handling may have made it more\nreproducible in fuzzing tests.\n\nFix this issue by adding missing error paths in nilfs_set_link(),\nnilfs_delete_entry(), and their caller nilfs_rename().","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":"nilfs2: handle errors that nilfs_prepare_chunk() may return","id":"CVE-2025-21721","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":"nilfs2: do not force clear folio if buffer is referenced","id":"CVE-2025-21722"},"packages":[],"prev":{"headline":"xfrm: delete intermediate secpath entry in packet offload mode","id":"CVE-2025-21720"},"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":"CWE Terms of Use","name":"CWE (MITRE)"},{"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 missing error check in the nilfs2 filesystem can cause a kernel crash via BUG_ON when directory rename operations encounter metadata errors.","url":"https://insights.sbomify.com/CVE-2025-21721/"}