{"vulnerability": "CVE-2025-21643", "sightings": [{"uuid": "9acc42ce-8076-4864-a376-e100c3352965", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2025-21643", "type": "seen", "source": "https://t.me/cvedetector/15836", "content": "{\n  \"Source\": \"CVE FEED\",\n  \"Title\": \"CVE-2025-21643 - \"CIFS Netfs Linux Kernel Async DIO Handling Vulnerability\"\", \n  \"Content\": \"CVE ID : CVE-2025-21643 \nPublished : Jan. 19, 2025, 11:15 a.m. | 35\u00a0minutes ago \nDescription : In the Linux kernel, the following vulnerability has been resolved:  \n  \nnetfs: Fix kernel async DIO  \n  \nNetfslib needs to be able to handle kernel-initiated asynchronous DIO that  \nis supplied with a bio_vec[] array.  Currently, because of the async flag,  \nthis gets passed to netfs_extract_user_iter() which throws a warning and  \nfails because it only handles IOVEC and UBUF iterators.  This can be  \ntriggered through a combination of cifs and a loopback blockdev with  \nsomething like:  \n  \n        mount //my/cifs/share /foo  \n        dd if=/dev/zero of=/foo/m0 bs=4K count=1K  \n        losetup --sector-size 4096 --direct-io=on /dev/loop2046 /foo/m0  \n        echo hello >/dev/loop2046  \n  \nThis causes the following to appear in syslog:  \n  \n        WARNING: CPU: 2 PID: 109 at fs/netfs/iterator.c:50 netfs_extract_user_iter+0x170/0x250 [netfs]  \n  \nand the write to fail.  \n  \nFix this by removing the check in netfs_unbuffered_write_iter_locked() that  \ncauses async kernel DIO writes to be handled as userspace writes.  Note  \nthat this change relies on the kernel caller maintaining the existence of  \nthe bio_vec array (or kvec[] or folio_queue) until the op is complete. \nSeverity: 0.0 | NA \nVisit the link for more details, such as CVSS details, affected products, timeline, and more...\",\n  \"Detection Date\": \"19 Jan 2025\",\n  \"Type\": \"Vulnerability\"\n}\n\ud83d\udd39 t.me/cvedetector \ud83d\udd39", "creation_timestamp": "2025-01-19T13:07:22.000000Z"}, {"uuid": "10240b5f-dfc8-4db5-925b-b5da8aa0ecfe", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2025-21643", "type": "seen", "source": "https://infosec.exchange/users/cve/statuses/113854718095653986", "content": "", "creation_timestamp": "2025-01-19T11:12:07.622745Z"}, {"uuid": "e0cd62c7-0de2-4338-a603-f94ddd0ae6fc", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2025-21643", "type": "seen", "source": "https://bsky.app/profile/cve-notifications.bsky.social/post/3lg3p46isrc2t", "content": "", "creation_timestamp": "2025-01-19T11:15:52.639435Z"}, {"uuid": "5d9a2ebf-9882-4e2b-b373-efd82cf5ea8f", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2025-21643", "type": "seen", "source": "https://bsky.app/profile/cve.skyfleet.blue/post/3lg3qyz7tax2q", "content": "", "creation_timestamp": "2025-01-19T11:49:57.328874Z"}, {"uuid": "09f0677a-04a4-46c7-97b6-2b548ce6501b", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2025-21643", "type": "published-proof-of-concept", "source": "https://t.me/DarkWebInformer_CVEAlerts/2323", "content": "\ud83d\udd17 DarkWebInformer.com - Cyber Threat Intelligence\n\ud83d\udccc CVE ID: CVE-2025-21643\n\ud83d\udd39 Description: In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix kernel async DIO\n\nNetfslib needs to be able to handle kernel-initiated asynchronous DIO that\nis supplied with a bio_vec[] array.  Currently, because of the async flag,\nthis gets passed to netfs_extract_user_iter() which throws a warning and\nfails because it only handles IOVEC and UBUF iterators.  This can be\ntriggered through a combination of cifs and a loopback blockdev with\nsomething like:\n\n        mount //my/cifs/share /foo\n        dd if=/dev/zero of=/foo/m0 bs=4K count=1K\n        losetup --sector-size 4096 --direct-io=on /dev/loop2046 /foo/m0\n        echo hello >/dev/loop2046\n\nThis causes the following to appear in syslog:\n\n        WARNING: CPU: 2 PID: 109 at fs/netfs/iterator.c:50 netfs_extract_user_iter+0x170/0x250 [netfs]\n\nand the write to fail.\n\nFix this by removing the check in netfs_unbuffered_write_iter_locked() that\ncauses async kernel DIO writes to be handled as userspace writes.  Note\nthat this change relies on the kernel caller maintaining the existence of\nthe bio_vec array (or kvec[] or folio_queue) until the op is complete.\n\ud83d\udccf Published: 2025-01-19T10:17:59.820Z\n\ud83d\udccf Modified: 2025-01-19T10:17:59.820Z\n\ud83d\udd17 References:\n1. https://git.kernel.org/stable/c/9f3a265836844eda30bf34c2584b8011fd4f0f49\n2. https://git.kernel.org/stable/c/3f6bc9e3ab9b127171d39f9ac6eca1abb693b731", "creation_timestamp": "2025-01-19T10:58:27.000000Z"}]}