--- id: CVE-2026-64600 title: |- In the Linux kernel, the following vulnerability has been resolved: xfs: resample the data fork mapping after cycling ILOCK xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapp… summary: |- In the Linux kernel, the following vulnerability has been resolved: xfs: resample the data fork mapping after cycling ILOCK xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapp… severity: high cvss: 7.8 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H' published: '2026-07-23' updated: '2026-07-27' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64600' references: - url: 'https://cdn2.qualys.com/advisory/2026/07/22/RefluXFS.txt' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/206c09b04dc5469c7ff14d8aceff2d47c88078d9' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/44f891bc088958399eec27f7604928694aa35581' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/50f0012da1040f69a4e788cd9aed587c9a04983f' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/b8c9aa832b52680ee40d6cab0efb081f9a69df05' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/dc11be133efca5fe3a2fb02b016dee825cc12f18' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/e705d81a7193dd19e69b8e2bad4696d78a4ea075' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'http://www.openwall.com/lists/oss-security/2026/07/22/14' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'http://www.openwall.com/lists/oss-security/2026/07/22/18' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'http://www.openwall.com/lists/oss-security/2026/07/22/19' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64600.json - url: 'https://access.redhat.com/security/cve/CVE-2026-64600' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2498915' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-64600' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64600' - url: 'https://access.redhat.com/errata/RHSA-2026:41062' - url: 'https://access.redhat.com/errata/RHSA-2026:39494' - url: 'https://access.redhat.com/errata/RHBA-2026:41013' - url: 'https://access.redhat.com/errata/RHSA-2026:41063' - url: 'https://access.redhat.com/errata/RHSA-2026:40425' - url: 'https://access.redhat.com/errata/RHBA-2026:39332' - url: 'https://access.redhat.com/errata/RHSA-2026:46951' - url: 'https://access.redhat.com/errata/RHSA-2026:39179' - url: 'https://access.redhat.com/errata/RHSA-2026:47998' - url: 'https://access.redhat.com/errata/RHSA-2026:39984' - url: 'https://access.redhat.com/errata/RHBA-2026:41254' - url: 'https://access.redhat.com/errata/RHSA-2026:41229' - url: 'https://access.redhat.com/errata/RHSA-2026:48016' - url: 'https://access.redhat.com/errata/RHSA-2026:47997' - url: 'https://access.redhat.com/errata/RHSA-2026:47984' - url: 'https://access.redhat.com/errata/RHSA-2026:47983' - url: 'https://access.redhat.com/errata/RHSA-2026:47981' - url: 'https://access.redhat.com/errata/RHSA-2026:39180' tags: - nvd - exploit-available - csaf - vex - red-hat - cve.org epss: 0.00467 epssPercentile: 0.40254 ingestedAt: '2026-07-27T06:16:48.977Z' exploits: github: 10 githubRepos: - 'https://github.com/0xBlackash/CVE-2026-64600' - 'https://github.com/Debajyoti0-0/CVE-2026-64600' - 'https://github.com/litosmartin/CVE-2026-64600-Refluxfs-PoC' checkedAt: '2026-10-27T19:07:31.004Z' exploitAvailable: true vendor: Red Hat product: Red Hat Enterprise Linux BaseOS E4S (v.9.4) affected: - enterprise_linux_for_nvidia 26 - enterprise_linux_appstream_eus_v_10_0 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_e4s_v_9_2 - enterprise_linux_appstream_e4s_v_9_4 - enterprise_linux_appstream_eus_v_9_6 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_eus_v_10_0 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_v_8 - enterprise_linux_baseos_aus_v_8_4 - enterprise_linux_baseos_eus_extension_v_8_4 - enterprise_linux_baseos_aus_v_8_6 - enterprise_linux_baseos_eus_extension_v_8_6 - enterprise_linux_baseos_e4s_v_8_8 - enterprise_linux_baseos_tus_v_8_8 - enterprise_linux_baseos_e4s_v_9_2 - enterprise_linux_baseos_e4s_v_9_4 - enterprise_linux_baseos_eus_v_9_6 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_eus_v_10_0 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_crb_v_8 - codeready_linux_builder_eus_v_9_6 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_eus_v_10_0 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_nfv_v_8 - enterprise_linux_real_time_for_nfv_e4s_v_9_4 - enterprise_linux_real_time_for_nfv_eus_v_9_6 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_eus_v_10_0 - enterprise_linux_real_time_v_10 - enterprise_linux_rt_v_8 - enterprise_linux_real_time_e4s_v_9_4 - enterprise_linux_real_time_eus_v_9_6 - enterprise_linux_real_time_v_9 patched: - enterprise_linux_appstream_eus_v_10_0 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_e4s_v_9_2 - enterprise_linux_appstream_e4s_v_9_4 - enterprise_linux_appstream_eus_v_9_6 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_eus_v_10_0 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_v_8 - enterprise_linux_baseos_aus_v_8_4 - enterprise_linux_baseos_eus_extension_v_8_4 - enterprise_linux_baseos_aus_v_8_6 - enterprise_linux_baseos_eus_extension_v_8_6 - enterprise_linux_baseos_e4s_v_8_8 - enterprise_linux_baseos_tus_v_8_8 - enterprise_linux_baseos_e4s_v_9_2 - enterprise_linux_baseos_e4s_v_9_4 - enterprise_linux_baseos_eus_v_9_6 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_eus_v_10_0 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_crb_v_8 - codeready_linux_builder_eus_v_9_6 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_eus_v_10_0 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_nfv_v_8 - enterprise_linux_real_time_for_nfv_e4s_v_9_4 - enterprise_linux_real_time_for_nfv_eus_v_9_6 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_eus_v_10_0 - enterprise_linux_real_time_v_10 - enterprise_linux_rt_v_8 - enterprise_linux_real_time_e4s_v_9_4 - enterprise_linux_real_time_eus_v_9_6 - enterprise_linux_real_time_v_9 cwe: - CWE-362 ssvc: exploitation: none automatable: 'no' technicalImpact: total timestamp: '2026-10-16T15:43:31.132977Z' --- ## Overview In the Linux kernel, the following vulnerability has been resolved: xfs: resample the data fork mapping after cycling ILOCK xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapping. Unfortunately, these two helpers cycle the ILOCK to grab a transaction, which means that the mappings are stale as soon as we reacquire the ILOCK. Currently we refresh the cow fork mapping by re-calling xfs_find_trim_cow_extent, but we don't refresh the data fork mapping beforehand, which means that the xfs_bmap_trim_cow in that function queries the refcount btree about the wrong physical blocks and returns an inaccurate value in *shared. If *shared is now false, the directio write proceeds with a stale data fork mapping. Fix this by querying the data fork mapping if the sequence counter changes across the ILOCK cycle. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **RHSA-2026:41062** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0), Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0), Red Hat Enterprise Linux Real Time EUS (v. 10.0) · released 2026-07-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:41062) - **RHSA-2026:39494** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10), Red Hat Enterprise Linux Real Time (v. 10) · released 2026-07-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:39494) - **RHBA-2026:41013** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux BaseOS E4S (v.9.2) · released 2026-07-16 · [advisory](https://access.redhat.com/errata/RHBA-2026:41013) - **RHSA-2026:41063** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux BaseOS E4S (v.9.4), Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4), Red Hat Enterprise Linux Real Time E4S (v.9.4) · released 2026-07-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:41063) - **RHSA-2026:40425** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat Enterprise Linux BaseOS EUS (v.9.6), Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6), Red Hat Enterprise Linux Real Time EUS (v.9.6) · released 2026-07-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:40425) - **RHBA-2026:39332** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9), Red Hat Enterprise Linux Real Time (v. 9) · released 2026-07-14 · [advisory](https://access.redhat.com/errata/RHBA-2026:39332) - **RHSA-2026:46951** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 10) · released 2026-07-27 · [advisory](https://access.redhat.com/errata/RHSA-2026:46951) - **RHSA-2026:39179** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8) · released 2026-07-14 · [advisory](https://access.redhat.com/errata/RHSA-2026:39179) - **RHSA-2026:47998** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8) · released 2026-07-29 · [advisory](https://access.redhat.com/errata/RHSA-2026:47998) - **RHSA-2026:39984** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS AUS (v.8.4), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) · released 2026-07-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:39984) - **RHBA-2026:41254** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS AUS (v.8.6), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) · released 2026-07-17 · [advisory](https://access.redhat.com/errata/RHBA-2026:41254) - **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux for NVIDIA 26 · no fix planned: Red Hat Enterprise Linux for NVIDIA 26 · updated 2026-09-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64600.json)