EUVD-2026-80561
GHSA-25fw-r826-pmc4
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local config/setup-time path (AV:L), needs privileged memory-hotplug/device-DAX control (PR:H) and specific compound-page alignment to trigger the wrong mapping (AC:H); impact is corruption/instability (I:L/A:H), no disclosure (C:N).
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
Lifecycle Timeline
7DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
powerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population
vmemmap_populate_compound_pages() uses addr_pfn to determine the PFN offset within a compound page and to decide whether the current vmemmap slot should be populated as a head page mapping or should reuse a tail page mapping.
However, addr_pfn is advanced manually in parallel with addr. The loop itself progresses in vmemmap address space, so each PAGE_SIZE step in addr covers PAGE_SIZE / sizeof(struct page) struct page slots. Since addr_pfn is compared against nr_pages in data-PFN units, it should advance by the same number of PFNs. The existing manual increments do not match that and therefore do not reliably track the PFN corresponding to the current addr.
As a result, pfn_offset can be computed from the wrong PFN and the code can make the head/tail decision for the wrong compound-page position.
Fix this by deriving addr_pfn directly from the current vmemmap address instead of carrying it as loop state.
AnalysisAI
Incorrect PFN bookkeeping in the Linux kernel's PowerPC compound vmemmap population path (vmemmap_populate_compound_pages) causes the kernel to compute the wrong pfn_offset and therefore make the head/tail struct-page mapping decision for the wrong position within a compound page, which can corrupt vmemmap contents or crash the system when PowerPC systems exercise compound-page vmemmap optimization (ZONE_DEVICE / device-DAX / persistent memory or memory-hotplug configurations). This is a deterministic setup- or boot-time arithmetic miscalculation rather than an attacker-controlled primitive: the vendor CVSS of 7.8 assumes local, low-privilege access with high confidentiality and integrity impact, but an independent re-assessment scores it CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H, noting the vendor vector appears over-scored because triggering the mis-decision requires high privileges to drive memory hotplug/device configuration, depends on specific compound-page population and alignment conditions, and has no remote or unauthenticated vector. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a powerpc (PPC) system that populates compound vmemmap via vmemmap_populate_compound_pages - i.e., ZONE_DEVICE / device-DAX / persistent-memory or memory-hotplug configurations that use compound-page vmemmap optimization. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The vendor CVSS is 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), but this signal is inconsistent with the actual nature of the defect and appears over-scored. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patches are available: update to Linux 6.6.157, 6.12.110, 6.18.51, 7.2.5, or 7.3-rc1 (or later) on the matching branch, which include the mainline fix commit f2b79c0d79683d552369bb9a7282c1f0226fc566 and its stable backports; verify the distro/kernel vendor has picked up the corresponding stable commit for the branch in use. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all PowerPC systems running Linux kernel versions affected by CVE-2026-89961, focusing on those with ZONE_DEVICE, device-DAX, persistent memory, or memory hotplug enabled. …
Sign in for detailed remediation steps and compensating controls.
Threat intelligence, references, and detailed analysis are available after sign-in.
Same technique Denial Of Service
View allShare
External POC / Exploit Code
Leaving vuln.today