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NVD / CVE Program· CNA Linux

CVE-2026-64533: fs/ntfs3: validate lcns_follow in log_replay conversion

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: 0.14% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 159f694d682e4215b3822ae31ed3a4631628fe55, 32b9f8733feb241627fa5f564b1a99b5cae974c5, 57c071e2c4f30b9c6f5aacb6679aab1269fbae99; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1.

Low priority for now. Upgrade to Linux Linux 159f694d682e4215b3822ae31ed3a4631628fe55, 32b9f8733feb241627fa5f564b1a99b5cae974c5, 57c071e2c4f30b9c6f5aacb6679aab1269fbae99; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1 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: fs/ntfs3: validate lcns_follow in log_replay conversion log_replay() converts DIR_PAGE_ENTRY_32 records into DIR_PAGE_ENTRY records when replaying version 0 restart tables. During this conversion, the memmove() length is derived directly from the on-disk lcns_follow field: memmove(&dp->vcn, &dp0->vcn_low, 2 * sizeof(u64) + le32_to_cpu(dp->lcns_follow) * sizeof(u64)); check_rstbl() validates restart table structure, but does not constrain per-entry lcns_follow values relative to the entry size. A malformed filesystem image can provide an oversized lcns_follow value, causing the conversion memmove() to access memory beyond the bounds of the allocated restart table buffer. The same field is later used to bound iteration over page_lcns[], so validating lcns_follow during conversion also prevents downstream out-of-bounds access from the same malformed metadata. Compute the maximum valid lcns_follow from the already-validated restart table entry size and reject entries that exceed this bound. Reuse the existing t16/t32 scratch variables already declared in log_replay() to avoid introducing new declarations. [almaz.alexandrovich@paragon-software.com: fixed the conflicts]

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Jul 27, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 3th 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%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-64533

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

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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.

—

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

    • 5.15affected
    • b46acd6a6a627d876898e1c84d3f84902264b445 and later · before ca343a99806b4fc8e27c48f08be3445c5fcd1445affected · git
    • b46acd6a6a627d876898e1c84d3f84902264b445 and later · before ddfc8683e1a627dbf1b83bacf8961443dd654258affected · git
    • b46acd6a6a627d876898e1c84d3f84902264b445 and later · before 57c071e2c4f30b9c6f5aacb6679aab1269fbae99affected · git
    • b46acd6a6a627d876898e1c84d3f84902264b445 and later · before 159f694d682e4215b3822ae31ed3a4631628fe55affected · git
    • b46acd6a6a627d876898e1c84d3f84902264b445 and later · before 7adb38279812c9c06b0e3fa7382f4d7887f3fa2daffected · git
    • b46acd6a6a627d876898e1c84d3f84902264b445 and later · before 32b9f8733feb241627fa5f564b1a99b5cae974c5affected · git
    • b46acd6a6a627d876898e1c84d3f84902264b445 and later · before 6a4c53a2e26a865565bd6a460961e8d6fcb32329affected · git
    • before 5.15not affected · semver
    • 5.15.212 and later · up to and including 5.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-64531Jul 27, 2026 · net: openvswitch: reject oversized nested action attrs
    31Monitor
  • ← EarlierCVE-2026-64532Jul 27, 2026 · fs/ntfs3: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation}
    31Monitor
  • Later →CVE-2026-64534Jul 27, 2026 · nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path
    39Monitor

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 Linux159f694d682e4215b3822ae31ed3a4631628fe55Vendor (CNA)
Linux Linux32b9f8733feb241627fa5f564b1a99b5cae974c5Vendor (CNA)
Linux Linux57c071e2c4f30b9c6f5aacb6679aab1269fbae99Vendor (CNA)
Linux Linux6a4c53a2e26a865565bd6a460961e8d6fcb32329Vendor (CNA)
Linux Linux7adb38279812c9c06b0e3fa7382f4d7887f3fa2dVendor (CNA)
Linux Linuxca343a99806b4fc8e27c48f08be3445c5fcd1445Vendor (CNA)
Linux Linuxddfc8683e1a627dbf1b83bacf8961443dd654258Vendor (CNA)
azl3 kernel 6.6.144.1-1 on Azure Linux 3.06.6.145.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package 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.

  • CVE-2026-7209819 days apartdm-verity: fix buffer overflow in FEC calculation
    39Monitor
  • CVE-2025-68811195 days apartsvcrdma: use rc_pageoff for memcpy byte offset
    39Monitor
  • CVE-2026-6812814 days apartice: reject out-of-range ptype in ice_parser_profile_init
    35Monitor
  • CVE-2026-645520 days apartvirtio-net: fix len check in receive_big()
    33Monitor
  • CVE-2026-645152 days apartwifi: mac80211: fix MLE defragmentation
    33Monitor
  • CVE-2026-6837614 days apartsctp: fix auth_hmacs array size in struct sctp_cookie
    32Monitor

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.
  • No account or password is required.
  • A user must open a link or visit a page.
  • 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
None
User interaction
Required
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:N/UI:R/S:U/C:H/I:H/A:H

nvd-secondary

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. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (6 more)

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

All records