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CVE Record

CVE-2026-64216: netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages()

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages() netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->no_unlock_folio so that it doesn't unlock a folio being read for netfs_perform_write() or netfs_write_begin(). However, given that netfs_unlock_abandoned_read_pages() is called _after_ NETFS_RREQ_IN_PROGRESS is cleared, the one folio that it's not allowed to dereference is the one specified by ->no_unlock_folio as ownership immediately reverts to the caller. Fix this by storing the folio pointer instead and using that rather than the index. Also fix netfs_unlock_read_folio() where the same applies.

CriticalCVSS 9.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

A Linux network-filesystem cleanup path may access a memory page after ownership has returned to another caller, creating a potential use-after-free. This can cause kernel instability or memory corruption; the supplied CVSS rates possible confidentiality, integrity, and availability impact as high. Actual exploitability is not established by the sources.

Executive priority

Treat as an urgent kernel patch-validation issue, especially for exposed or high-value Linux systems using network filesystems. Schedule expedited vendor-supported updates, but avoid claiming confirmed remote compromise: the supplied severity is critical while real-world reachability and exploitation remain unproven.

Technical view

After NETFS_RREQ_IN_PROGRESS is cleared, netfs_unlock_abandoned_read_pages() may dereference the folio identified by no_unlock_folio even though ownership has reverted to the caller. The correction stores and compares the folio pointer instead of accessing its index. The same ownership issue is corrected in netfs_unlock_read_folio().

Likely exposure

Systems running affected Linux kernel branches and exercising the relevant netfs read or write paths are candidates. The bundle names 6.12, 6.12.106, 6.18.34, 7.0.11, and 7.1, but its range formatting is ambiguous and includes an unexplained “0.” Distribution backports mean version strings alone are insufficient.

Exploitation context

The source reports a potential kernel use-after-free and assigns CVSS 9.8 with network reachability, low complexity, and no required privileges or interaction. However, it supplies no reproducer, attack prerequisites, or evidence of exploitation. The CVE is not listed as KEV in the provided bundle.

Researcher notes

The sources establish the ownership-ordering flaw and four stable fix commits, but provide no CWE, reproducer, affected filesystem list, exploit analysis, or demonstrated impact. The affected-version data appears structurally ambiguous. Researchers should distinguish theoretical CVSS reachability from verified attack paths and rely on distribution backport records when assessing individual hosts.

Mitigation direction

  • Apply a vendor-supported kernel update containing the applicable referenced stable fix.
  • Check distribution advisories for backported fixes and precise affected package versions.
  • Prioritize systems using network filesystems or workloads that exercise netfs read and write paths.
  • Use vendor guidance for temporary risk reduction if immediate kernel replacement is unavailable.

Validation and detection

  • Inventory kernel and distribution package versions across Linux systems.
  • Confirm whether each kernel package contains an applicable referenced fix commit or vendor backport.
  • Identify systems and workloads using the relevant netfs paths.
  • Review kernel logs for crashes or memory-corruption symptoms, without treating absence as proof of safety.
  • Recheck vendor advisories because the supplied affected-version boundaries are incomplete.
Prepared
Confidence
medium
Sources
6

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-2026-64216 mapping review

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.8 (3.1)
Known Exploited
No
Published

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

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.

1CVSS vectors
3Timeline events
0ADP providers
5Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.8CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

9.8Critical
CVSS 3.1 vector shape for CVE-2026-64216Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
LinuxLinuxee4cdf7ba857a894ad1650d6ab77669cbbfa329e, ee4cdf7ba857a894ad1650d6ab77669cbbfa329e, ee4cdf7ba857a894ad1650d6ab77669cbbfa329e, ee4cdf7ba857a894ad1650d6ab77669cbbfa329eunaffected
LinuxLinux6.12, 0, 6.12.106, 6.18.34, 7.0.11, 7.1affected
Weakness

CWE details

No CWE listed

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