CVE-2026-64600

HIGH

xfs: resample the data fork mapping after cycling ILOCK

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 6 public exploits for CVE-2026-64600. PoCs published by letsr00t, bha-vin, Debajyoti0-0.

AI-analyzed exploit summary This repository provides a bash script that checks for the presence of CVE-2026-64600 (RefluxFS) vulnerability by analyzing kernel version, XFS filesystem configurations, and patch indicators. It does not contain exploit code but detects potential vulnerability conditions.

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.

Exploits (6)

github SCANNER
by letsr00t · shellpoc
https://github.com/letsr00t/RefluxFS_CVE-2026-64600

This repository provides a bash script that checks for the presence of CVE-2026-64600 (RefluxFS) vulnerability by analyzing kernel version, XFS filesystem configurations, and patch indicators. It does not contain exploit code but detects potential vulnerability conditions.

Classification
Scanner 98%
Attack Type
Other
Complexity
Trivial
Reliability
Reliable
Target: Linux Kernel (XFS/RefluxFS implementation)
Auth required
Prerequisites: Local user access · XFS filesystem with reflink enabled · Unpatched Linux kernel
mistral-large-3 · analyzed Jul 28, 2026 Full analysis →
github WORKING POC
by bha-vin · cpoc
https://github.com/bha-vin/CVE-2026-64600-Exploit

Exploits a race condition in the Linux kernel XFS copy-on-write (reflink) path to achieve local privilege escalation by clearing the root password in /etc/passwd. Uses multi-threaded O_DIRECT writes to trigger the vulnerability.

Classification
Working Poc 98%
Attack Type
Lpe
Complexity
Moderate
Reliability
Racy
Target: Linux kernel (XFS filesystem) versions affected by CVE-2026-64600 (RefluXFS)
No auth needed
Prerequisites: XFS filesystem with reflink=1 enabled · Writable directory on the same XFS volume as /etc/passwd · Affected kernel version (unpatched)
mistral-large-3 · analyzed Jul 28, 2026 Full analysis →
nomisec WORKING POC
by Debajyoti0-0 · poc
https://github.com/Debajyoti0-0/CVE-2026-64600

This repository provides a detection and mitigation tool for CVE-2026-64600, a race condition in the Linux kernel's XFS filesystem (RefluXFS) affecting reflink-enabled volumes. The PoC safely verifies the vulnerability by triggering a non-destructive race condition and offers layered mitigation (SystemTap probe + remount with reflink=0).

Classification
Working Poc 98%
Attack Type
Other
Complexity
Moderate
Reliability
Racy
Target: Linux kernel (4.11 through 6.12.95, 6.18.38, 7.1.3, and 7.2-rc1 to 7.2-rc3) with XFS filesystem and reflink enabled
No auth needed
Prerequisites: Linux system with vulnerable kernel version · XFS filesystem with reflink enabled · Root privileges for mitigation deployment
mistral-large-3 · analyzed Jul 26, 2026 Full analysis →
nomisec SUSPICIOUS
by vulnquest58 · poc
https://github.com/vulnquest58/VQ-RefluxCore

The repository claims to be an 'advanced weaponized exploit framework' for CVE-2026-64600 (RefluXFS kernel LPE), but the provided Bash script is a non-functional stub with no actual exploit code. It contains extensive marketing language, hardcoded credentials, and framework scaffolding without demonstrating the vulnerability mechanics.

Classification
Suspicious 95%
Attack Type
Lpe
Complexity
Complex
Reliability
Theoretical
Target: Linux Kernel (RefluXFS module, versions >= 4.11)
No auth needed
Prerequisites: Vulnerable Linux kernel version (>= 4.11) · Access to unprivileged user shell
mistral-large-3 · analyzed Jul 25, 2026 Full analysis →
github STUB
by HORKimhab · poc
https://github.com/HORKimhab/CVE-2026-64600

This repository contains no actual exploit code, technical details, or vulnerability analysis for CVE-2026-64600. It only includes a README with donation requests, setup instructions for a Python virtual environment, and legal disclaimers, but no functional PoC or research content.

Classification
Stub 95%
Attack Type
Other
Complexity
Trivial
Reliability
Theoretical
Target: unspecified
No auth needed
mistral-large-3 · analyzed Jul 23, 2026 Full analysis →
nomisec STUB
by 0xBlackash · poc
https://github.com/0xBlackash/CVE-2026-64600

This repository claims to analyze CVE-2026-64600, a Linux kernel memory corruption vulnerability in the RefluxFS filesystem implementation leading to local privilege escalation. However, it contains no actual exploit code, technical details, or proof-of-concept, only high-level descriptions and placeholder documentation.

Classification
Stub 95%
Attack Type
Lpe
Complexity
Unknown
Reliability
Unknown
Target: Linux Kernel (RefluxFS filesystem implementation)
Auth required
Prerequisites: Local user access · Ability to interact with RefluxFS filesystem
mistral-large-3 · analyzed Jul 23, 2026 Full analysis →

Scores

CVSS v3 7.8
EPSS 0.0049
EPSS Percentile 39.2%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Details

Status published
Products (23)
linux/Kernel 4.11.0 - 5.15.212linux
linux/Kernel 4.11.0 - 6.12.96linux
linux/Kernel 5.16.0 - 6.1.178linux
linux/Kernel 6.13.0 - 6.18.39linux
linux/Kernel 6.19.0 - 7.1.4linux
linux/Kernel 6.2.0 - 6.6.145linux
linux/Kernel 6.7.0 - 6.12.96linux
Linux/Linux < 4.11
Linux/Linux 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 - 206c09b04dc5469c7ff14d8aceff2d47c88078d9
Linux/Linux 3c68d44a2b49a0ac9165faa9c191e1e618c8a8d5 - 2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7
... and 13 more
Published Jul 23, 2026
Tracked Since Jul 23, 2026