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NVD / CVE Program· CNA Linux

CVE-2026-64063: netfs: Fix streaming write being overwritten

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 20195925c768626dc901a4781a51e508702c88ad, 7b4dcf1b9455a6e52ac7478b4057dbe10359576d, cdae00e8e215d95911d95f100599e187b6560de5.

Low priority for now. Upgrade to Linux Linux 20195925c768626dc901a4781a51e508702c88ad, 7b4dcf1b9455a6e52ac7478b4057dbe10359576d, cdae00e8e215d95911d95f100599e187b6560de5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix streaming write being overwritten In order to avoid reading whilst writing, netfslib will allow "streaming writes" in which dirty data is stored directly into folios without reading them first. Such folios are marked dirty but may not be marked uptodate. If a folio is entirely written by a streaming write, uptodate will be set, otherwise it will have a netfs_folio struct attached to ->private recording the dirty region. In the event that a partially written streaming write page is to be overwritten entirely by a single write(), netfs_perform_write() will try to copy over it, but doesn't discard the netfs_folio if it succeeds; further, it doesn't correctly handle a partial copy that overwrites some of the dirty data. Fix this by the following: (1) If the folio is successfully overwritten, free the netfs_folio struct before marking the page uptodate. (2) If the copy to the folio partially fails, but short of the dirty data, just ignore the copy. (3) If the copy partially fails and overwrites some of the dirty data, accept the copy, update the netfs_folio struct to record the new data. If the folio is now filled, free the netfs_folio and set uptodate, otherwise return a partial write. Found with: fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \ /xfstest.test/junk --replay-ops=junk.fsxops using the following as junk.fsxops: truncate 0x0 0 0x927c0 write 0x63fb8 0x53c8 0 copy_range 0xb704 0x19b9 0x24429 0x79380 write 0x2402b 0x144a2 0x90660 * write 0x204d5 0x140a0 0x927c0 * copy_range 0x1f72c 0x137d0 0x7a906 0x927c0 * read 0x00000 0x20000 0x9157c read 0x20000 0x20000 0x9157c read 0x40000 0x20000 0x9157c read 0x60000 0x20000 0x9157c read 0x7e1a0 0xcfb9 0x9157c on cifs with the default cache option. It shows folio 0x24 misbehaving if the FMODE_READ check is commented out in netfs_perform_write(): if (//(file->f_mode & FMODE_READ) || netfs_is_cache_enabled(ctx)) { and no fscache. This was initially found with the generic/522 xfstest.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Jul 19, 2026
Updated
Sep 2, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel6.12 and later · before 6.12.92
  • linux linux kernel6.13 and later · before 6.18.34
  • linux linux kernel6.19 and later · before 7.0.11
  • linux linux kernel7.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 6.12affected
    • 8f52de0077ba3bf41e5d53d67a185700f41efce7 and later · before 20195925c768626dc901a4781a51e508702c88adaffected · git
    • 8f52de0077ba3bf41e5d53d67a185700f41efce7 and later · before ef9b521212e4863814ef7dfe19889abaf55ca840affected · git
    • 8f52de0077ba3bf41e5d53d67a185700f41efce7 and later · before cdae00e8e215d95911d95f100599e187b6560de5affected · git
    • 8f52de0077ba3bf41e5d53d67a185700f41efce7 and later · before 7b4dcf1b9455a6e52ac7478b4057dbe10359576daffected · git
    • before 6.12not affected · semver
    • 6.12.92 and later · up to and including 6.12.*not affected · semver
    • 6.18.34 and later · up to and including 6.18.*not affected · semver
    • 7.0.11 and later · up to and including 7.0.*not affected · semver
    • 7.1 and laternot affected · original_commit_for_fix

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:13linuxbefore 6.12.94-16.12.94-1
Debian:14linuxbefore 7.0.12-17.0.12-1
openSUSE:Leap 16.0dtb-aarch64before 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-64kbbefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-azurebefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-defaultbefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-default-basebefore 6.12.0-160000.40.1.160000.2.296.12.0-160000.40.1.160000.2.29
openSUSE:Leap 16.0kernel-docsbefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-kvmsmallbefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-obs-buildbefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-obs-qabefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-rtbefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-sourcebefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-symsbefore 6.12.0-160000.40.16.12.0-160000.40.1
openSUSE:Leap 16.0kernel-zfcpdumpbefore 6.12.0-160000.40.16.12.0-160000.40.1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-64061Jul 19, 2026 · netfs: Fix early put of sink folio in netfs_read_gaps()
    39Monitor
  • ← EarlierCVE-2026-64062Jul 19, 2026 · netfs: Fix potential deadlock in write-through mode
    22Monitor
  • Later →CVE-2026-64064Jul 19, 2026 · netfs: Fix netfs_invalidate_folio() to clear dirty bit if all changes gone
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux20195925c768626dc901a4781a51e508702c88adVendor (CNA)
Linux Linux7b4dcf1b9455a6e52ac7478b4057dbe10359576dVendor (CNA)
Linux Linuxcdae00e8e215d95911d95f100599e187b6560de5Vendor (CNA)
Linux Linuxef9b521212e4863814ef7dfe19889abaf55ca840Vendor (CNA)
debian:linux6.12.94-1 · Debian:13Package registry (OSV)
opensuse:dtb-aarch646.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-64kb6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-azure6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-default-base6.12.0-160000.40.1.160000.2.29 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-docs6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-kvmsmall6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-build6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-obs-qa6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-rt6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-source6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:kernel-syms6.12.0-160000.40.1 · openSUSE:Leap 16.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records