PatchSiren cyber security CVE debrief

CVE-2026-64156 Linux CVE debrief

A vulnerability was found in the Linux kernel's netfs and afs components. The issue is related to write skipping in dir/link writepages. The fix involves modifying netfs_write_single() and afs_single_writepages() to better handle skipped writes due to lock contention and WB_SYNC_NONE. This change ensures that if a skip occurs, the inode is re-marked as the VFS may have cleared the mark. The vulnerability has a medium defensive priority, and Linux kernel users and administrators should take necessary precautions to ensure their systems are updated with the latest kernel patches.

Vendor: Linux
Product: Unknown
CVSS: MEDIUM 5.5
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-07-19
Original CVE updated: 2026-08-13
Advisory published: 2026-07-19
Advisory updated: 2026-08-13

Who should care

Linux kernel users and administrators should be aware of this vulnerability and take necessary precautions to ensure their systems are updated with the latest kernel patches. This includes reviewing system logs for potential issues and monitoring for suspicious activity.

Technical summary

The vulnerability is caused by a problem in the netfs and afs components of the Linux kernel. Specifically, the netfs_write_single() and afs_single_writepages() functions do not properly handle writes that are skipped due to lock contention and WB_SYNC_NONE. This can lead to issues with directory and link writepages. The fix involves modifying these functions to return 1 if a skip occurs and re-marking the inode as necessary. The affected products are Linux kernel deployments, and the vulnerability has a medium defensive priority.

Defensive priority

Medium

Recommended defensive actions

Update the Linux kernel to the latest version
Review and apply kernel patches
Monitor system logs for potential issues
Review compensating controls for exposed systems while remediation is scheduled and verified
Check relevant monitoring, detection, and logs for exposed assets that need extra review
Track exceptions, retest remediated assets, and close the item only after evidence is documented
Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-19T16:17:57.603Z and has not been modified since then. The NVD entry is currently Received. There is limited information available about the vulnerability, and further verification is needed to understand the affected scope and potential impact.

Sources and references

Verified primary and authoritative sources

CVE-2026-64156 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-64156

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-64156 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-64156

NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Source reference
Unverified legacy reference

URL: https://git.kernel.org/stable/c/77bb293049d61e04c12b24ebbffafaf5ab36af90

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Source reference
Unverified legacy reference

URL: https://git.kernel.org/stable/c/9871938f99cc6cb266a77265491660e2375271f5

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Source reference
Unverified legacy reference

URL: https://git.kernel.org/stable/c/f91e10435c0dd37c48b1b25e6236284f656ddc0c

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.