Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4 powerpc vmemmap_populate_compound_pages comparison

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k0.00-

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4 and classified as very critical. The impacted element is the function vmemmap_populate_compound_pages of the component powerpc. Executing a manipulation can lead to comparison. This vulnerability appears as CVE-2026-89961. The attack may be performed from remote. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.156/6.12.109/6.18.50/7.2.4. It has been declared as very critical. This vulnerability affects the function vmemmap_populate_compound_pages of the component powerpc. The manipulation with an unknown input leads to a comparison vulnerability. The CWE definition for the vulnerability is CWE-697. The product compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-89961 since 09/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/16/2026).

Upgrading to version 6.6.157, 6.12.110, 6.18.51, 7.2.5 or 7.3-rc1 eliminates this vulnerability. Applying the patch b96be860673f9fbbf12cdadb0b25fc4d6d4d207f/e163c7184acf36ac20a248498f4a16016057ca01/9c914b7a0bd18834505c65f22225ce22c152b2d9/7968852a7ca3ce81477ec5b4494a28d612f35a97/89a4ae32764172468dea303eb6ae90fe6c859712 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Comparison
CWE: CWE-697
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.157/6.12.110/6.18.51/7.2.5/7.3-rc1
Patch: b96be860673f9fbbf12cdadb0b25fc4d6d4d207f/e163c7184acf36ac20a248498f4a16016057ca01/9c914b7a0bd18834505c65f22225ce22c152b2d9/7968852a7ca3ce81477ec5b4494a28d612f35a97/89a4ae32764172468dea303eb6ae90fe6c859712

Timelineinfo

09/11/2026 CVE reserved
09/16/2026 +5 days Advisory disclosed
09/16/2026 +0 days VulDB entry created
09/16/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89961 (🔒)
GCVE (CVE): GCVE-0-2026-89961
GCVE (VulDB): GCVE-100-405808

Entryinfo

Created: 09/16/2026 15:05
Changes: 09/16/2026 15:05 (59)
Complete: 🔍
Cache ID: 216::103

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