Security readout for executives and security teams
Plain-English summary
A Linux kernel debugging test can leave stale page-table entries after cleanup. If kernel memory is later reused, another process may encounter corrupted memory-management state, potentially affecting confidentiality, integrity, or availability. The issue is primarily relevant to kernels built with CONFIG_DEBUG_VM_PGTABLE enabled, which limits typical production exposure.
Executive priority
Treat as high technical severity but scope remediation by configuration. Quickly inventory debug-enabled kernels, especially shared testing platforms and systems permitting untrusted local users. Normal production fleets without CONFIG_DEBUG_VM_PGTABLE enabled are likely lower priority, pending vendor confirmation.
Technical view
The mm/debug_vm_pgtable test manually allocates an mm_struct and page-table entries but did not clear those entries in destroy_args(). Reuse of the same allocation can expose a subsequent process to stale mappings, producing invalid counters, warnings, or memory corruption. CVSS 3.1 is 7.0: local, high-complexity, low-privilege exploitation without user interaction.
Likely exposure
Highest exposure is in debug, development, testing, or custom Linux kernels with CONFIG_DEBUG_VM_PGTABLE=y. Standard production kernels without that configuration are unlikely to reach the vulnerable test path. The supplied affected-version data includes Linux 5.15 through 6.17 ranges, but distribution backports require vendor-specific verification.
Exploitation context
The CVSS vector requires local access, low privileges, and high attack complexity. The source demonstrates the fault occurring in practice on a debug kernel, but supplies no evidence of deliberate exploitation. CVE-2025-39776 is not listed as KEV in the bundle, so active exploitation should not be claimed.
Researcher notes
The failure is a stale page-table cleanup defect involving reuse of an mm_struct allocation. The demonstrated outcome includes page-table accounting corruption and kernel warnings. Although CVSS assigns high confidentiality, integrity, and availability impacts, the supplied evidence does not establish a reliable exploitation technique or observed attacks.
Mitigation direction
- Identify systems running kernels built with CONFIG_DEBUG_VM_PGTABLE enabled.
- Install a vendor-supported kernel containing the referenced stable fix.
- Prioritize debug or test hosts that process untrusted local workloads.
- Check distribution and appliance advisories for backported remediation details.
Validation and detection
- Confirm the running kernel version and distribution build identifier.
- Inspect kernel configuration for CONFIG_DEBUG_VM_PGTABLE=y.
- Verify vendor changelogs reference CVE-2025-39776 or the stable fix.
- Review kernel logs for debug_vm_pgtable warnings, bad RSS counters, or non-zero pgtables_bytes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2025-39776 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H15.9LinuxVulnerability scoring details
Base CVSS 3.1 score
7HighVector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/7bf57a0709cd7c9088cea8de023d6f4fbf2518b0CVE reference, Linux
- https://git.kernel.org/stable/c/47d2a149611b8a94d24add9868c442a4af278658CVE reference, Linux
- https://git.kernel.org/stable/c/63962ff932ef359925b94be2a88df6b4fd4fed0aCVE reference, Linux
- https://git.kernel.org/stable/c/61a9f2e5c49f05e3ea2c16674540a075a1b4be6fCVE reference, Linux
- https://git.kernel.org/stable/c/561171db3b3eb759ba3f284dba7a76f4476ade03CVE reference, Linux
- https://git.kernel.org/stable/c/dde30854bddfb5d69f30022b53c5955a41088b33CVE reference, Linux
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlCVE reference, CVE
- https://cert-portal.siemens.com/productcert/html/ssa-032379.htmlCVE reference, siemens-SADP
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.