---
cve: "CVE-2026-64600"
severity: "HIGH"
cvss: 7.8
epss: "47%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-07-23 06:16:50"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T16:00:08+02:00"
---

# CVE-2026-64600

> 7.8 HIGH

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 5.15.212
- Kernel ≥ 6.1.178
- Kernel ≥ 6.6.145
- Kernel ≥ 6.12.96
- Kernel ≥ 6.18.39
- Kernel ≥ 7.1.4

## Referenzen

- <https://git.kernel.org/stable/c/dc11be133efca5fe3a2fb02b016dee825cc12f18>
- <https://git.kernel.org/stable/c/b8c9aa832b52680ee40d6cab0efb081f9a69df05>
- <https://git.kernel.org/stable/c/50f0012da1040f69a4e788cd9aed587c9a04983f>
- <https://git.kernel.org/stable/c/e705d81a7193dd19e69b8e2bad4696d78a4ea075>
- <https://git.kernel.org/stable/c/206c09b04dc5469c7ff14d8aceff2d47c88078d9>
- <https://git.kernel.org/stable/c/44f891bc088958399eec27f7604928694aa35581>
- <https://git.kernel.org/stable/c/2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7>
- <https://cdn2.qualys.com/advisory/2026/07/22/RefluXFS.txt>
- <http://www.openwall.com/lists/oss-security/2026/07/22/14>
- <http://www.openwall.com/lists/oss-security/2026/07/22/18>
- <http://www.openwall.com/lists/oss-security/2026/07/22/19>
- <http://www.openwall.com/lists/oss-security/2026/07/31/3>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-64600) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_