SEPTEMBER 7, 2026
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Case File

CVE-2026-64158

HIGH · CVSS 7.3 EPSS 0.08%

Source: NVD + CISA KEV + EPSS · Published 2026-07-19 · Last synced 2026-08-18

CyberRota Analysis

AI-Generated

The vulnerability affects the Linux kernel's netfs module, specifically its handling of write streaming when file descriptors are opened in read-write mode (O_RDWR). This flaw can lead to inefficient data handling and potential data corruption, particularly when multiple file descriptors are used for reading and writing simultaneously. Organizations using Linux-based systems, especially those relying on netfs for file operations, should prioritize patching this vulnerability to mitigate risks associated with data integrity and performance issues.

CVE
CVE-2026-64158
Severity
HIGH
CVSS
7.3
EPSS
0.08%
Linux

Original NVD Description

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix write streaming disablement if fd open O_RDWR In netfs_perform_write(), "write streaming" (the caching of dirty data in dirty but !uptodate folios) is performed to avoid the need to read data that is just going to get immediately overwritten. However, this is/will be disabled in three circumstances: if the fd is open O_RDWR, if fscache is in use (as we need to round out the blocks for DIO) or if content encryption is enabled (again for rounding out purposes). The idea behind disabling it if the fd is open O_RDWR is that we'd need to flush the write-streaming page before we could read the data, particularly through mmap. But netfs now fills in the gaps if ->read_folio() is called on the page, so that is unnecessary. Further, this doesn't actually work if a separate fd is open for reading. Fix this by removing the check for O_RDWR, thereby allowing streaming writes even when we might read. This caused a number of problems with the generic/522 xfstest, but those are now fixed.

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