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Linux KernelOperating system · Linux

CVE-2026-52971

HIGH · 7.8 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 6.18.33 / 7.0.10 or later.
See remediation →
80/100
Remediation priority · High
Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: net: ena: PHC: Fix potential use-after-free in get_timestamp Move the phc->active check and resp pointer assignment to after acquiring the spinlock. Previously, phc->active was checked without holding the lock, and resp was cached from ena_dev->phc.virt_addr before the lock was acquired. If ena_com_phc_destroy() runs between the lockless active check and the lock acquisition, it sets active=false, releases the lock, frees the DMA memory, and sets virt_addr=NULL. The get_timestamp path would then read a NULL virt_addr and dereference it. With both the active check and the pointer read under the lock, destroy cannot free the memory while get_timestamp is using it.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Race condition in Linux kernel ena driver PHC (Physical Hardware Clock) where get_timestamp checked phc->active and read virt_addr without holding a spinlock. If ena_com_phc_destroy() ran concurrently, it could set active=false, free the DMA memory, and set virt_addr=NULL while get_timestamp was executing, leading to a use-after-free when dereferencing the NULL pointer.

MitigationApply the kernel patch which moves both the active check and pointer read under the spinlock, preventing the destroy function from freeing memory while get_timestamp is using it. This is a code-level fix requiring kernel rebuild.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.17, < 6.18.33>= 6.19, < 7.0.10= 7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check kernel version against affected range
    Run 'uname -r' or 'cat /proc/version' to get the running kernel version. Compare it to the affected ranges: < 6.18.33, >= 6.19 to < 7.0.10, or 7.1
    Affected if The installed kernel version falls within any of these ranges: >= 6.17 and < 6.18.33, or >= 6.19 and < 7.0.10, or exactly 7.1
  2. Verify ena driver is loaded
    Run 'lsmod | grep ena' or check '/sys/module/ena/' exists. The driver is named 'ena' or 'ena_elastic'
    Affected if The ena (Elastic Network Adapter) kernel module is loaded on the system
  3. Confirm system uses ENA network interface
    Run 'ip link show' or 'ethtool -i <interface>' to identify network interfaces and check their driver. Look for interfaces using the 'ena' driver
    Affected if Any network interface is bound to the ena driver (typically on AWS EC2 instances with ENA-enabled NICs)
  4. Check if PHC (Physical Hardware Clock) is configured
    Inspect driver configuration or runtime state by checking '/sys/class/net/*/device/' for PHC-related files, or review dmesg for 'phc' or 'Physical Hardware Clock' messages related to ena
    Affected if The ena driver has PHC functionality enabled or configured on the system

The system is affected if it runs a vulnerable kernel version AND uses the ena driver with PHC functionality enabled, as the race condition only triggers when get_timestamp and ena_com_phc_destroy execute concurrently on the PHC code path.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.18.33 / 7.0.10 or later
Fixed in 6.18.337.0.10
Interim mitigation

Apply the kernel patch which moves both the active check and pointer read under the spinlock, preventing the destroy function from freeing memory while get_timestamp is using it. This is a code-level fix requiring kernel rebuild.

Recommended fix High confidence

6.18.33, 7.0.10, or 7.1.1+ (depending on your current branch)

  1. Upgrade the Linux kernel to version 6.18.33 or later if using the 6.18.x branch
  2. Upgrade the Linux kernel to version 7.0.10 or later if using the 7.0.x branch
  3. Upgrade the Linux kernel to version 7.1.1 or later if using the 7.1.x branch
  4. After upgrading, verify the kernel version matches one of the fixed releases using: uname -r
Caveat Kernel upgrades may require system reboot and could have compatibility implications with custom modules or specific hardware configurations

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-52971 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data