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CVE Record

CVE-2026-23109: fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()

In the Linux kernel, the following vulnerability has been resolved: fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() Above the while() loop in wait_sb_inodes(), we document that we must wait for all pages under writeback for data integrity. Consequently, if a mapping, like fuse, traditionally does not have data integrity semantics, there is no need to wait at all; we can simply skip these inodes. This restores fuse back to prior behavior where syncs are no-ops. This fixes a user regression where if a system is running a faulty fuse server that does not reply to issued write requests, this causes wait_sb_inodes() to wait forever.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-23109 is a Linux kernel availability bug. On systems using FUSE-like mappings without data-integrity semantics, a faulty FUSE server that does not answer write requests can make sync-related kernel writeback waiting hang indefinitely. The public sources do not indicate code execution or active exploitation.

Executive priority

Treat this as a targeted availability risk, not an emergency remote-code-execution issue based on current evidence. Prioritize patching where FUSE-backed workloads support critical services or where prior hang symptoms have appeared.

Technical view

The fix changes fs/writeback wait_sb_inodes() to skip mappings marked AS_NO_DATA_INTEGRITY. The CVE describes a regression where wait_sb_inodes() waits forever for writeback completion even though FUSE traditionally has no data-integrity wait semantics. Kernel stable commits are listed as the remediation references.

Likely exposure

Exposure is most relevant to Linux systems running affected kernels and FUSE or similar user-space filesystem workloads. Exact exposure depends on distribution kernel versioning and backports; the source bundle lists Linux as affected but does not provide a clear distro matrix.

Exploitation context

CISA KEV is false, and the provided sources do not report active exploitation. The described trigger requires a faulty FUSE server that does not reply to issued write requests, causing an indefinite wait and service or system availability impact.

Researcher notes

The source bundle lacks CVSS, CWE, distro-specific affected ranges, and proof of exploitation. Analysis should stay tied to the stated regression: wait_sb_inodes() waiting indefinitely on AS_NO_DATA_INTEGRITY mappings when a FUSE server fails to respond.

Mitigation direction

  • Apply distribution kernel updates that include the referenced stable fixes.
  • Track vendor advisories for affected kernel packages and backports.
  • Prioritize hosts using FUSE or user-space filesystem services.
  • Monitor for sync or writeback hangs involving FUSE workloads.
  • If patching is delayed, reduce reliance on unreliable FUSE services.

Validation and detection

  • Inventory Linux kernel versions across production and staging systems.
  • Check whether FUSE or user-space filesystem workloads are present.
  • Confirm vendor kernel packages include the referenced stable commits.
  • Review logs and incidents for sync, writeback, or FUSE hang symptoms.
  • Test patched kernels in staging before broad rollout.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-23109 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
3Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux0c58a97f919c24fe4245015f4375a39ff05665b6, 0c58a97f919c24fe4245015f4375a39ff05665b6unaffected
LinuxLinux6.16, 0, 6.18.8, 6.19affected
Weakness

CWE details

No CWE listed

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