CVE-2026-89644
kernel: btrfs: fix extent map leak in NOCOW direct I/O write
Severity
LowRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · September 11, 2026
Updated · September 29, 2026
Description
A flaw was found in the Linux kernel's btrfs filesystem. When performing direct I/O writes in a NOCOW (No Copy-On-Write) range, an extent map reference may not be properly released if an error occurs during extent creation. This oversight can lead to an extent map leak, potentially causing memory exhaustion or system instability, which could result in a Denial of Service (DoS).
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.1 · 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE-772 · Missing Release of Resource after Effective Lifetime