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Linux KernelOperating system · Linux

CVE-2026-46115

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-28
Fix available
A fix is available. Upgrade to 6.6.140 / 6.12.88 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

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: block: add pgmap check to biovec_phys_mergeable biovec_phys_mergeable() is used by the request merge, DMA mapping, and integrity merge paths to decide if two physically contiguous bvec segments can be coalesced into one. It currently has no check for whether the segments belong to different dev_pagemaps. When zone device memory is registered in multiple chunks, each chunk gets its own dev_pagemap. A single bio can legitimately contain bvecs from different pgmaps -- iov_iter_extract_bvecs() breaks at pgmap boundaries but the outer loop in bio_iov_iter_get_pages() continues filling the same bio. If such bvecs are physically contiguous, biovec_phys_mergeable() will coalesce them, making it impossible to recover the correct pgmap for the merged segment via page_pgmap(). Add a zone_device_pages_have_same_pgmap() check to prevent merging bvec segments that span different pgmaps.

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

In the Linux kernel, biovec_phys_mergeable() lacks validation that bvec segments belong to the same dev_pagemap. When zone device memory is registered in multiple chunks (each with its own pgmap), a single bio can contain bvecs from different pgmaps that are physically contiguous. The function incorrectly coalesces these segments, making it impossible to recover the correct pgmap via page_pgmap(), potentially leading to incorrect DMA operations or memory corruption.

MitigationApply the kernel patch adding zone_device_pages_have_same_pgmap() check to biovec_phys_mergeable() to prevent merging bvec segments across different pgmaps; update to a kernel version containing this fix.

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:>= 6.2, < 6.6.140>= 6.7, < 6.12.88>= 6.13, < 6.18.30>= 6.19, < 7.0.7

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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 your kernel version
    Run `uname -r` to get the running kernel version
    Affected if The version falls within >= 6.2, < 6.6.140 OR >= 6.7, < 6.12.88 OR >= 6.13, < 6.18.30 OR >= 6.19, < 7.0.7
  2. Determine if zone device memory is in use
    Look for /dev/pmem* devices (persistent memory), check `ls -la /sys/bus/platform/devices/` for zone_device drivers, or check dmesg for 'zone device memory' messages
    Affected if The system has any zone device memory (pmem, GPU memory, or other dev_pagemap memory) registered with multiple pgmap instances
  3. Check for multiple dev_pagemap instances
    Search kernel logs (dmesg) or debugfs for entries showing multiple pgmap structures, or inspect /sys/kernel/debug/device-grid for zone device page mappings
    Affected if More than one pgmap (dev_pagemap) is registered for zone device memory segments
  4. Verify if biovec_phys_mergeable has the pgmap check
    Inspect the kernel symbol `biovec_phys_mergeable` in /proc/kallsyms or vmlinux, or check for the presence of `zone_device_pages_have_same_pgmap` symbol in the running kernel
    Affected if The function does not contain or call any pgmap validation logic, meaning the fix is not applied
  5. Check for memory corruption indicators
    Review dmesg for unexpected memory corruption errors, data integrity failures, or DMA mapping errors related to bio or bvec operations on zone device memory
    Affected if Any memory corruption or integrity errors involve biovecs from zone device memory regions

You are affected if your kernel version is in the vulnerable range AND you have zone device memory with multiple pgmaps, and the biovec_phys_mergeable function lacks the pgmap validation check.

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 6.6.140 / 6.12.88 / 6.18.30 or later
Fixed in 6.6.1406.12.886.18.30
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch adding zone_device_pages_have_same_pgmap() check to biovec_phys_mergeable() to prevent merging bvec segments across different pgmaps; update to a kernel version containing this fix.

Recommended fix High confidence

Upgrade to one of: Linux kernel 6.6.140+, 6.12.88+, 6.18.30+, or 7.0.7+ (depending on your current branch)

  1. Identify the currently running kernel version using 'uname -r'
  2. Determine which stable kernel branch your version belongs to (6.2-6.6.x, 6.7-6.12.x, 6.13-6.18.x, or 6.19-7.0.x)
  3. Upgrade to the fixed kernel version for your branch: 6.6.140 or later for 6.2-6.6.x, 6.12.88 or later for 6.7-6.12.x, 6.18.30 or later for 6.13-6.18.x, or 7.0.7 or later for 6.19-7.0.x
  4. Update bootloader configuration if needed (e.g., update-grub for GRUB)
  5. Reboot the system into the new kernel
  6. Verify the fix is applied by checking the kernel version matches the fixed release
Caveat Kernel upgrades may require rebuild of out-of-tree kernel modules; ensure compatible drivers/modules exist for the target version before rebooting

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
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,860
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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-2026-46115 in production — separate from our analysis above.

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What this is

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