{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-93255 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-93255 is a vulnerability in Linux, published on 24 Sep 2026. 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-2026-93255 and fix it if it is affected.\n\nWhat it is: CVE-2026-93255 is a vulnerability in Linux, published on 24 Sep 2026. 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-2026-93255 in the wild and no public exploit code.\n\nAffected product: Linux. 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-2026-93255/ (Markdown: https://insights.sbomify.com/CVE-2026-93255/index.md)","id":"CVE-2026-93255","markdown":"https://insights.sbomify.com/CVE-2026-93255/index.md","name":"CVE-2026-93255","record":{"aliases":["DEBIAN-CVE-2026-93255","GHSA-vp7r-5mv7-7v8c","UBUNTU-CVE-2026-93255"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel filesystem","requires_auth":"low_privilege","summary":"A race condition in the Linux kernel btrfs filesystem can trigger a kernel warning and potential denial of service during unmount operations.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":null,"severity":null,"source":null,"vector":null,"version":null},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: make sure EXTENT_BUFFER_READING is cleared under refs_lock\n\n[FALSE ALERTS]\nThere is a bug report that the warning inside\ninvalidate_and_check_btree_folios() got triggered during btrfs/298:\n\n BTRFS info (device sdd): first mount of filesystem f9bf732a-a19b-44b9-99a7-614ddff168e2\n BTRFS info (device sdd): using crc32c checksum algorithm\n BTRFS error (device sdd): failed to find fsid cb2fdb42-b638-4f2f-badd-4127467ba674 when attempting to open seed devices\n BTRFS error (device sdd): failed to read chunk tree: -2\n ------------[ cut here ]------------\n WARNING: disk-io.c:3342 at invalidate_and_check_btree_folios+0x260/0x3c0 [btrfs], CPU#4: mount/125993\n CPU: 4 UID: 0 PID: 125993 Comm: mount Tainted: G        W  OE       7.1.0-rc7-custom+ #1 PREEMPT(full)\n Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20250812-19.fc42 08/12/2025\n Call trace:\n  invalidate_and_check_btree_folios+0x260/0x3c0 [btrfs] (P)\n  open_ctree+0x1f50/0x23b0 [btrfs]\n  btrfs_get_tree+0x89c/0xc48 [btrfs]\n  vfs_get_tree+0x30/0x110\n  vfs_cmd_create+0x58/0xe8\n  __arm64_sys_fsconfig+0x39c/0x518\n  invoke_syscall.constprop.0+0x48/0x120\n  el0_svc_common.constprop.0+0x40/0xe8\n  do_el0_svc+0x24/0x38\n  el0_svc+0x50/0x310\n  el0t_64_sync_handler+0xa0/0xe8\n  el0t_64_sync+0x198/0x1a0\n ---[ end trace 0000000000000000 ]---\n BTRFS warning (device sdd): unable to release extent buffer 365985792 owner 3 gen 17 refs 3 flags 0x5\n\n[CAUSE]\nIn that invalidate_and_check_btree_folios() we wait for the eb to finish\nits read, then check if it's only held by us and the btree inode.\n\nIf not, then do a warning as it may be still held, and could cause\nproblems.\n\nBut there is a small window where the check can lead to false alerts:\n\n    Thread A (Read endio)         |        Thread B (Unmount)\n----------------------------------+-------------------------------------\n end_bbio_meta_read()             |\n | The eb has one extra ref held  |\n | by the reader, and has         |\n | EXTENT_BUFFER_READING flag set | invalidate_and_check_btree_folios()\n |                                | |\n |- clear_extent_buffer_reading() | |\n |                                | |- wait_on_bit_io();\n |                                | |  The EXTENT_BUFFER_READING flag is\n |                                | |  cleared\n |                                | |- if (refcount_read(eb-\u003erefs) \u003e 2)\n |                                |    The eb is held by the read, us\n |                                |    and btree inode, thus it\n |                                |    will trigger the warning\n |- free_extent_buffer()          |\n\n[FIX]\nIntroduce a helper, free_extent_buffer_clear_reading().\n\nIf the new parameter, @clear_reading, is set, we will hold the spinlock\nat the beginning of free_extent_buffer_clear_reading() to make sure the\nEXTENT_BUFFER_READING flag is cleared inside the same critical section\nof decreasing refs.\n\nNow free_extent_buffer() will just call\nfree_extent_buffer_clear_reading() with @clear_reading set to false, so\nno behavior change.\n\nBut for end_bbio_meta_read(), it will not clear_extent_buffer_reading()\ndirectly, but pass @clear_reading as true.\n\nThen inside invalidate_and_check_btree_folios(), hold the refs_lock\nbefore reading refs.\nSo that we eliminate the race window completely.","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":"btrfs: make sure EXTENT_BUFFER_READING is cleared under refs_lock","id":"CVE-2026-93255","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"race_condition","year":"2026"},"n_packages":0,"n_references":3,"next":{"headline":"arm64: hibernate: mask DAIF before restoring hibernated kernel","id":"CVE-2026-93256"},"packages":[],"prev":{"headline":"arm64: entry: Avoid unnecessary local_irq_disable() on kernel exit","id":"CVE-2026-93254"},"products":["Linux"],"published":"2026-09-24","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-10-19","vendors":["Linux"]},"summary":"A race condition in the Linux kernel btrfs filesystem can trigger a kernel warning and potential denial of service during unmount operations.","url":"https://insights.sbomify.com/CVE-2026-93255/"}