# CVE-2026-64600: xfs: resample the data fork mapping after cycling ILOCK > A race condition in the Linux kernel XFS filesystem allows stale data fork mappings, potentially leading to incorrect data reads or writes during direct I/O operations. - **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 23 Jul 2026 - **Updated:** 19 Oct 2026 - **Also known as:** AZL-93050, BELL-CVE-2026-64600, CLSA-2026-1784277735, CLSA-2026-1784278790, DEBIAN-CVE-2026-64600, GHSA-6p99-w6f4-qcvq, RHBA-2026:39321, RHBA-2026:39332, RHBA-2026:41013, RHBA-2026:41254, RHSA-2026:46951, RHSA-2026:47981, RHSA-2026:47983, RHSA-2026:47984, RHSA-2026:47997, RHSA-2026:47998, RHSA-2026:48016, ROOT-OS-DEBIAN-12-CVE-2026-64600, ROOT-OS-UBUNTU-2204-CVE-2026-64600, UBUNTU-CVE-2026-64600 ## What is CVE-2026-64600? CVE-2026-64600 is a high-severity vulnerability in Linux kernel, published on 23 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description 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. Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) ## Which versions are affected by CVE-2026-64600? It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `kpatch-patch-6_12_0-211_16_1` | Red Hat:enterprise_linux:10.2 | All versions | 0:1-5.el10_2 | | `kpatch-patch-6_12_0-211_16_1-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 0:1-5.el10_2 | | `kpatch-patch-6_12_0-211_16_1-debugsource` | Red Hat:enterprise_linux:10.2 | All versions | 0:1-5.el10_2 | | `kpatch-patch-4_18_0-553_109_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-8.el8_10 | | `kpatch-patch-4_18_0-553_109_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-8.el8_10 | | `kpatch-patch-4_18_0-553_109_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-8.el8_10 | | `kpatch-patch-4_18_0-553_125_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-5.el8_10 | | `kpatch-patch-4_18_0-553_125_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-5.el8_10 | | `kpatch-patch-4_18_0-553_125_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-5.el8_10 | | `kpatch-patch-4_18_0-553_53_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-15.el8_10 | | `kpatch-patch-4_18_0-553_53_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-15.el8_10 | | `kpatch-patch-4_18_0-553_53_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-15.el8_10 | | `kpatch-patch-4_18_0-553_72_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-12.el8_10 | | `kpatch-patch-4_18_0-553_72_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-12.el8_10 | | `kpatch-patch-4_18_0-553_72_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-12.el8_10 | | `kpatch-patch-4_18_0-553_85_1` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-10.el8_10 | | `kpatch-patch-4_18_0-553_85_1-debuginfo` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-10.el8_10 | | `kpatch-patch-4_18_0-553_85_1-debugsource` | Red Hat:enterprise_linux:8::baseos | All versions | 0:1-10.el8_10 | | `kernel-64k-debug-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-64k-debug-devel` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-64k-debug-devel-matched` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-64k-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-64k-devel` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-64k-devel-matched` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debug-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debug-devel` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debug-devel-matched` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debuginfo-common-aarch64` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debuginfo-common-ppc64le` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debuginfo-common-s390x` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-debuginfo-common-x86_64` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-devel` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-devel-matched` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-doc` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-rt-64k-debug-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-rt-64k-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-rt-debug-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-rt-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | | `kernel-tools-debuginfo` | Red Hat:enterprise_linux:9::appstream | All versions | 0:5.14.0-687.26.1.el9_8 | Products: Linux kernel. ## How do I fix CVE-2026-64600? Apply the vendor's patch. ## Is CVE-2026-64600 being exploited? There is no known exploitation of CVE-2026-64600 in the wild and no public exploit code. Public exploit code: - CVE-2026-64600 (github_poc): https://github.com/0xredash/CVE-2026-64600 - A C-based Linux security utility for detecting, safely verifying (Proof of Concept), and mitigating CVE-2026-64600 (RefluXFS). It provides kernel vulnerability assessment, XFS reflink detection, a safe race-condition PoC, and layered mitigation using SystemTap and XFS hardening. (github_poc): https://github.com/Debajyoti0-0/CVE-2026-64600 - A POC for the recently discovered Qualys bug on COW with XFS (github_poc): https://github.com/litosmartin/CVE-2026-64600-Refluxfs-PoC - A Linux kernel local privilege escalation affecting the XFS filesystem copy-on-write (CoW) path. (github_poc): https://github.com/masrikky/CVE-2026-64600-RefluXFS - CVE-2026-64600 - Draft - Check todo (github_poc): https://github.com/HORKimhab/CVE-2026-64600 - is an advanced security research framework designed to model, analyze, and demonstrate Local Privilege Escalation (LPE) mechanics associated with kernel-level race conditions and filesystem structure vulnerabilities (CVE-2026-64600 / RefluXFS) (github_poc): https://github.com/vulnquest58/VQ-RefluxCore ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-64600 and fix it if it is affected. What it is: CVE-2026-64600 is a high-severity vulnerability in Linux kernel, published on 23 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-64600 in the wild and no public exploit code. Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. 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. 2. 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. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-64600/ (Markdown: https://insights.sbomify.com/CVE-2026-64600/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64600 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64600 - OSV: https://osv.dev/vulnerability/CVE-2026-64600 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-64600/ Summaries are generated and may contain mistakes; the official description above is the record.