{"id":"CVE-2026-89644","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix extent map leak in NOCOW direct I/O write\n\nbtrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an\nextent map reference that must be dropped on al…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix extent map leak in NOCOW direct I/O write\n\nbtrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an\nextent map reference that must be dropped on al…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-772"],"vendor":"Linux","product":"Linux","affected":["Linux >= 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af < b7c873765875645b11503f94c9bae2ca80127375","Linux >= 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af < f42efd634c0ae7ba0ce2fc5e30e291b0803b0ae2","Linux >= 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af < 05a1a816eef8b3e4332620a64fc8cf45c4eb5c0d","Linux >= 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af < 3f950867c307c5413d628a153ac44915bd117ffd","Linux 4.7"],"published":"2026-09-11","updated":"2026-09-21","sourceUpdated":"2026-09-21T14:17:24.403","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89644","references":[{"url":"https://git.kernel.org/stable/c/05a1a816eef8b3e4332620a64fc8cf45c4eb5c0d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3f950867c307c5413d628a153ac44915bd117ffd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b7c873765875645b11503f94c9bae2ca80127375","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f42efd634c0ae7ba0ce2fc5e30e291b0803b0ae2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89644.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89644"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532063"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89644"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89644"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89644.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00166,"epssPercentile":0.06254,"cvssSource":"vendor","ingestedAt":"2026-09-14T11:11:19.885Z","slug":"CVE-2026-89644","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix extent map leak in NOCOW direct I/O write\n\nbtrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an\nextent map reference that must be dropped on all exit paths.\n\nFor direct writes into a NOCOW range, btrfs_get_blocks_direct_write()\nkeeps using that extent map and asks btrfs_create_dio_extent() to\nallocate the ordered extent. If that fails, for example because\nbtrfs_alloc_ordered_extent() fails, the function returns the error\nwithout dropping the input extent map. The PREALLOC path avoided this by\ndropping the input extent map before replacing it with the newly created\none.\n\nCheck the error from btrfs_create_dio_extent() before replacing the\nmap and drop the input extent map on failure.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10 · no fix planned: Red Hat Enterprise Linux 10 · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89644.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":204171,"id":"CVE-2026-89644","ts":1789490235781,"field":"cvss","old":null,"new":"5.5"},{"seq":204170,"id":"CVE-2026-89644","ts":1789490235781,"field":"severity","old":"none","new":"medium"},{"seq":147794,"id":"CVE-2026-89644","ts":1789270212315,"field":"cvss","old":null,"new":"5.5"},{"seq":147793,"id":"CVE-2026-89644","ts":1789270212315,"field":"severity","old":"none","new":"medium"},{"seq":109542,"id":"CVE-2026-89644","ts":1789183732347,"field":"cvss","old":null,"new":"5.5"},{"seq":109541,"id":"CVE-2026-89644","ts":1789183732347,"field":"severity","old":"none","new":"medium"}]}