Linux Kernel up to 6.18.52 xen/gntalloc drivers/xen/gntalloc.c gntalloc_ioctl_alloc allocation of resources

CVSS Meta Temp Score
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CTI Interest Score
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8.4$0-$5k1.67-

Summaryinfo

A vulnerability identified as very critical has been detected in Linux Kernel up to 6.18.52. This impacts the function gntalloc_ioctl_alloc of the file drivers/xen/gntalloc.c of the component xen/gntalloc. This manipulation causes allocation of resources. This vulnerability is registered as CVE-2026-98900. The attack needs to be launched locally. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as very critical was found in Linux Kernel up to 6.18.52. Affected by this vulnerability is the function gntalloc_ioctl_alloc of the file drivers/xen/gntalloc.c of the component xen/gntalloc. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: xen/gntalloc: validate grant count before allocation gntalloc_ioctl_alloc() allocates the grant-id array before checking whether the requested count fits within the global grant limit. Counts above that limit cannot succeed, so reject them before the user-controlled allocation reaches kcalloc(). Use a subtraction-based check while holding gref_mutex so adding the requested count cannot wrap. Also cast the count before advancing the per-file index so the page-size multiplication is performed in 64-bit arithmetic.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-98900 since 09/25/2026. The exploitation appears to be easy. An attack has to be approached locally. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/23/2026).

Upgrading to version 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111 or 6.18.53 eliminates this vulnerability. Applying the patch e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8/71a0cf87e19fb35c4292ca88985e376e613c900a/641de086a05f349de7fc548612432bc2fed721ca/720554c04acba80018ded069d3e0984bebaee891/84d5727cef8eb9c8a28210ad248f1c70b223b065/231542f4e43cf9837cb520664545e85fbe666b7b/2299822f3f466b5dcad2377bf63986199f881a6b is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-108856). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.8
VulDB Meta Temp Score: 8.4

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
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: Allocation of resources
CWE: CWE-770 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

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 5.10.271/5.15.222/6.1.189/6.6.158/6.12.111/6.18.53
Patch: e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8/71a0cf87e19fb35c4292ca88985e376e613c900a/641de086a05f349de7fc548612432bc2fed721ca/720554c04acba80018ded069d3e0984bebaee891/84d5727cef8eb9c8a28210ad248f1c70b223b065/231542f4e43cf9837cb520664545e85fbe666b7b/2299822f3f466b5dcad2377bf63986199f881a6b

Timelineinfo

09/25/2026 CVE reserved
10/23/2026 +28 days Advisory disclosed
10/23/2026 +0 days VulDB entry created
10/23/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98900 (🔒)
GCVE (CVE): GCVE-0-2026-98900
GCVE (VulDB): GCVE-100-425665
EUVD: 🔒

Entryinfo

Created: 10/23/2026 14:23
Updated: 10/23/2026 15:59
Changes: 10/23/2026 14:23 (60), 10/23/2026 15:59 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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