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Linux Kernel EUVDEUVD-2026-45633

| CVE-2026-64060 MEDIUM
Memory Leak (CWE-401)
2026-07-19 Linux GHSA-hp9w-255m-3fwf
Linux
5.5
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Recon
    Authenticate as local low-privilege user
  2. Delivery
    Access netfs-backed mount (NFS/Ceph/AFS)
  3. Exploit
    Trigger or coincide with network errors causing netfs_wait_for_read() failure
  4. Install
    Each failed write leaks one request reference
  5. C2
    Repeat at volume over time
  6. Execute
    Kernel memory exhausted
  7. Impact
    System availability degraded or crash

Vulnerability Assessment

Weakness
CWE
CWE-401
ASVS 5.0
V15 - Secure Coding and Architecture Resource cleanup, leak prevention
Exploitation Conditions

Requires a local low-privilege user account (PR:L per CVSS). The target system must have a network filesystem backed by the Linux netfs layer - specifically NFS, Ceph, AFS, or another netfs-integrated filesystem - actively mounted and accessible to the attacker. Error conditions from netfs_wait_for_read() must be inducible, either via natural network instability or by positioning the attacker to disrupt the network path to the file server. Systems with no netfs-backed mounts are entirely unaffected. The leak occurs only in the error path of netfs_write_begin(), not during normal successful write operations, so sustained error-path triggering is necessary for meaningful resource exhaustion.
Impact

The CVSS 3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H accurately frames this as a local-only, low-privilege, availability-only concern. EPSS at 0.17% (6th percentile) confirms no meaningful exploitation interest in the wild. There is no CISA KEV entry, no public proof-of-concept, and no oss-security weaponization discussion beyond the fix notification. Real-world impact is further constrained by the requirement that a network filesystem backed by the netfs layer must be actively mounted and reachable under degraded network conditions; systems with no NFS, Ceph, or AFS mounts are unaffected. The leak accumulates only in error paths, not normal write operations, making rapid resource exhaustion unlikely without deliberate effort. This vulnerability warrants routine kernel update scheduling rather than emergency response - even routine patch cycles should cover it within standard maintenance windows.
Exploit ScenarioDerived

A local user with a standard unprivileged account on a server mounting a Ceph or NFS share repeatedly issues write calls to a file on that mount while a simulated or genuine network disruption causes netfs_wait_for_read() to return errors. Each failed write leaks one netfs_io_request allocation; after a large number of such failures, kernel slab memory is exhausted and the system becomes unavailable or crashes. No public proof-of-concept exists for this scenario.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 02, 2026

Reference leak in the Linux kernel netfs subsystem exposes systems with network filesystem mounts to a local denial-of-service condition. The netfs_write_begin() function fails to drop its held reference on the netfs request object when netfs_wait_for_read() returns an error, violating reference-counting invariants in the kernel's network filesystem abstraction layer. A low-privileged local user who can trigger repeated write errors on a netfs-backed mount (NFS, Ceph, AFS, or similar) can slowly exhaust kernel memory resources. No public exploit code exists and EPSS is 0.17% (6th percentile), consistent with a low-priority kernel maintenance fix.

RemediationAI

Update the Linux kernel to a patched version: 6.18.34, 7.0.11, or 7.1 or later. Ubuntu users should apply the update detailed in USN-8593-1 (https://ubuntu.com/security/notices/USN-8593-1). For distributions not yet shipping patched kernels, the upstream stable commits are available for manual backporting from git.kernel.org. As a compensating control on systems that cannot be patched immediately, unmounting or disabling all netfs-backed network filesystem mounts (NFS, Ceph, AFS) eliminates the vulnerable code path entirely, though this will disrupt access to network-attached storage and should only be considered where the operational impact is acceptable. No other targeted workarounds exist for the refcount leak itself short of a kernel patch.

Affected VersionsENISA

Linux 4090b31422a6f24dfe701e31ffec7ba5804a7e2f <28686d6d8b60dc5bbae9ef6023ab2051d6c66cdf
Linux 4090b31422a6f24dfe701e31ffec7ba5804a7e2f <5046a34f0643441f05b0253ea64e1a3af87efe14
Linux 5.18
Linux 4090b31422a6f24dfe701e31ffec7ba5804a7e2f <22ae28aae43623be235ff455558cdd13fbe2daeb
Linux patch: 0
Linux patch: 7.0.11
Linux patch: 6.18.34
Linux patch: 7.1

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Technical ContextAI · show details

The Linux kernel netfs subsystem (cpe:2.3:a:linux:linux) provides a generic read/write helper layer shared across network filesystems including NFS, Ceph, AFS, and Samba/CIFS. The netfs_write_begin() function implements the folio-based write-start path: it populates the page cache by waiting for a pending read via netfs_wait_for_read(). When that wait returns an error - for example due to a network fault or server-side failure - the function's error path returns without releasing the reference it holds on the netfs_io_request object. CWE-401 (Missing Release of Memory after Effective Lifetime) describes this class precisely: the request allocation remains pinned beyond its useful lifetime, leaking memory in an unbounded fashion across repeated error events. The introduced-by commit is 4090b31422a6f24dfe701e31ffec7ba5804a7e2f; the fix corrects the refcount drop in all relevant error branches.

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Severity by source

NVD PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI 5.5 MEDIUM

Local low-privilege access required; resource leak impacts only availability with no confidentiality or integrity consequences per description.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE MEDIUM
Red Hat 5.5 LOW

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
CVSS changed
Sep 02, 2026 - 21:22 NVD
5.5 (MEDIUM)
Patch available
Jul 19, 2026 - 17:03 EUVD
CVE Published
Jul 19, 2026 - 15:39 cve.org
UNKNOWN (no severity yet)
CVE Published
Jul 19, 2026 - 15:39 nvd
MEDIUM 5.5

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

netfs: Fix leak of request in netfs_write_begin() error handling

Fix netfs_write_begin() to not leak our ref on the request in the event that we get an error from netfs_wait_for_read().

Threat Intelligence Overview

EPSS Score
0.2%
Top 94% exploitable
Prevalence
Ubiquitous
Linux kernel present in nearly all server, cloud, and embedded deployments
Data Quality
6 sources
Confidence: High
EUVD 🇯🇵JVN NVD CVE.org EPSS MSRC Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
High

Priority Score

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Same weakness CWE-401 – Memory Leak

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 16.0 Affected

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-64060 ADVISORY https://seclists.org/oss-sec/2026/q3/230 ADVISORY https://ubuntu.com/security/notices/USN-8593-1 ADVISORY https://vuldb.com/vuln/380245 REF https://git.kernel.org/stable/c/22ae28aae43623be235ff455558cdd13fbe2daeb REF https://git.kernel.org/stable/c/28686d6d8b60dc5bbae9ef6023ab2051d6c66cdf REF https://git.kernel.org/stable/c/5046a34f0643441f05b0253ea64e1a3af87efe14 REF https://git.kernel.org/stable/c/9192f304379187b396d56d6a1a406712c6bfa5a3

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