CVE-2026-64157
Medium · 5.5CVSS
5.5
EPSS
0.2%
Published
Jul 19, 2026
CISA due date
—
Cloudanix analysis
A bug in the Linux kernel's file-write handling can let a local user crash the system or corrupt data during certain write operations.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Low
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Improper Input Validation
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Incorrect update to finfo->dirty_offset in netfs_invalidate_folio when a partial invalidation overlaps the front of a dirty streaming-write folio, causing the dirty region to be advanced to the wrong boundary instead of the end of the invalidated range.
Why it matters to the business
Local processes performing streaming writes through the netfs layer may experience data corruption, lost writes, or kernel crashes, disrupting file I/O workloads on Linux systems.
How an attack unfolds
A local attacker triggers netfs_invalidate_folio on a partially dirtied streaming-write folio so that the erroneous offset calculation leaves an incorrect dirty region, which later produces inconsistent page state and triggers a kernel fault or data-integrity failure during subsequent writeback.
How to fix it
Apply the upstream fix that sets finfo->dirty_offset to iend in netfs_invalidate_folio; upgrade to a Linux kernel release containing this change.
How to confirm the fix worked
Inspect the netfs_invalidate_folio implementation to confirm the assignment uses the end of the invalidation region rather than its start; run regression tests that exercise partial invalidations of streaming-write folios.
Typical attack path
- Obtain local user access on an affected Linux kernel
- Perform or induce streaming writes that allocate netfs folios with partial dirty ranges
- Cause targeted invalidation (e.g., via truncate, hole punch, or direct I/O) that overlaps only the front of a dirty folio
- Trigger the buggy offset assignment and subsequent writeback or folio release to induce crash or corruption
How to detect it
Review kernel logs for oops/panic messages referencing netfs_invalidate_folio or folio dirty-region handling; correlate with processes performing streaming writes and invalidation operations.
What your security team should do
- Prioritize kernel updates on systems that use netfs-based filesystems or FUSE
- Monitor vendor advisories for the specific kernel version containing the fix
- Limit untrusted local code execution until patches are deployed
The record
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix partial invalidation of streaming-write folio In netfs_invalidate_folio(), if the region of a partial invalidation overlaps the front (but not all) of a dirty write cached in a streaming write page (dirty, but not uptodate, with the dirty region tracked by a netfs_folio struct), the function modifies the dirty region - but incorrectly as it moves the region forward by setting the start to the start, not the end, of the invalidation region. Fix this by setting finfo->dirty_offset to the end of the invalidation region (iend).
Affected packages
| Ecosystem | Package | Introduced | Fixed |
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