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VulnerabilityPublished Updated

CVE-2026-98939: Linux kernel · x86/mm: Drop unnecessary PMD page copy when freeing

Affects Linux kernelSource GCVE Database

0
Authoritative record:CVE-2026-98939· Medium

Not known to be exploited.

Data as of 28 Oct 2026, 02:15 UTC

Severity
Medium

Rated by Threat Radar · CVSS not yet scored by NVD

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-5.5 – 7.0.0-38.38
23 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1003.3 – 7.0.0-1017.17
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
13 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=resoluteOther threatsAffected
  • 6.19.0-1002.2 – 7.0.0-1015.15
13 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1013.13
15 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix for this vulnerability has been implemented by removing the unnecessary PMD page copy and changing the page freeing logic to avoid the locking cycle. Users should apply the updated Linux kernel versions that include this fix. The affected versions are explicitly listed and should be upgraded or patched accordingly.

Description

CVE-2026-98939 is a vulnerability in the Linux kernel related to the x86 memory management subsystem. It involves an unnecessary PMD page copy operation during page freeing, which causes a potential deadlock due to circular locking dependencies involving the mmap_lock and pool_shrink_rwsem locks. The issue arises when the kernel attempts to avoid hardware setting Accessed=1 bits in unreachable page table entries, which is unnecessary. The fix removes the PMD copy, detaches the PMD page at the PUD level, flushes mid-level caches, and frees PTE tables directly, eliminating the problematic allocation and locking cycle.

References

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