CVE-2026-98939: Linux kernel · x86/mm: Drop unnecessary PMD page copy when freeing
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 28 Oct 2026, 02:15 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
Exploitation evidence
Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=resoluteOther threats | Affected
| 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
- ubuntu.com/security/CVE-2026-98939 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98939 (opens in a new tab)
- git.kernel.org/stable/c/d3c2d2692bdf4af94bb27bc7a3aa0a348a567606 (opens in a new tab)
- git.kernel.org/stable/c/e3ee38c1bc0b11a8d3e63dce7050759b61864286 (opens in a new tab)
- git.kernel.org/stable/c/f38c57a28ebbd057471573e39555d5aa11ab03cf (opens in a new tab)