CVE-2026-98900

xen/gntalloc: validate grant count before allocation

Published Oct 23, 2026 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed

Description

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`dd3140588d9551235ebc2a0dacdca098e7677573`	affected	< e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8
`dd3140588d9551235ebc2a0dacdca098e7677573`	affected	< 71a0cf87e19fb35c4292ca88985e376e613c900a
`dd3140588d9551235ebc2a0dacdca098e7677573`	affected	< 641de086a05f349de7fc548612432bc2fed721ca
`dd3140588d9551235ebc2a0dacdca098e7677573`	affected	< 720554c04acba80018ded069d3e0984bebaee891
`dd3140588d9551235ebc2a0dacdca098e7677573`	affected	< 84d5727cef8eb9c8a28210ad248f1c70b223b065
`dd3140588d9551235ebc2a0dacdca098e7677573`	affected	< 231542f4e43cf9837cb520664545e85fbe666b7b
`dd3140588d9551235ebc2a0dacdca098e7677573`	affected	< 2299822f3f466b5dcad2377bf63986199f881a6b

Linux

affected

Version	Status	Constraints
`2.6.39`	affected	—
`0`	unaffected	< 2.6.39
`5.10.271`	unaffected	≤ 5.10.*
`5.15.222`	unaffected	≤ 5.15.*
`6.1.189`	unaffected	≤ 6.1.*
`6.6.158`	unaffected	≤ 6.6.*
`6.12.111`	unaffected	≤ 6.12.*
`6.18.53`	unaffected	≤ 6.18.*
`7.2`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Version	Status	Scheme	Platform
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,71a0cf87e19fb35c4292ca88985e376e613c900a)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,641de086a05f349de7fc548612432bc2fed721ca)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,720554c04acba80018ded069d3e0984bebaee891)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,84d5727cef8eb9c8a28210ad248f1c70b223b065)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,231542f4e43cf9837cb520664545e85fbe666b7b)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,2299822f3f466b5dcad2377bf63986199f881a6b)`	affected	code_commit	—
`[0,5.10.271)`	affected	semver	—
`[0,5.15.222)`	affected	semver	—
`[0,6.1.189)`	affected	semver	—
`[0,6.6.158)`	affected	semver	—
`[0,6.12.111)`	affected	semver	—
`[0,6.18.53)`	affected	semver	—

Linux

Version	Status	Scheme	Platform
`[5.10.271,5.11.0)`	unaffected	semver	—
`[5.15.222,5.16.0)`	unaffected	semver	—
`[6.1.189,6.2.0)`	unaffected	semver	—
`[6.6.158,6.7.0)`	unaffected	semver	—
`[6.12.111,6.13.0)`	unaffected	semver	—
`[6.18.53,6.19.0)`	unaffected	semver	—
`[7.2,*]`	unaffected	generic	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,71a0cf87e19fb35c4292ca88985e376e613c900a)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,641de086a05f349de7fc548612432bc2fed721ca)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,720554c04acba80018ded069d3e0984bebaee891)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,84d5727cef8eb9c8a28210ad248f1c70b223b065)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,231542f4e43cf9837cb520664545e85fbe666b7b)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,2299822f3f466b5dcad2377bf63986199f881a6b)`	affected	code_commit	—
`[0,5.10.271)`	affected	semver	—
`[0,5.15.222)`	affected	semver	—
`[0,6.1.189)`	affected	semver	—
`[0,6.6.158)`	affected	semver	—
`[0,6.12.111)`	affected	semver	—
`[0,6.18.53)`	affected	semver	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[5.10.271,5.11.0)`	unaffected	semver	—
`[5.15.222,5.16.0)`	unaffected	semver	—
`[6.1.189,6.2.0)`	unaffected	semver	—
`[6.6.158,6.7.0)`	unaffected	semver	—
`[6.12.111,6.13.0)`	unaffected	semver	—
`[6.18.53,6.19.0)`	unaffected	semver	—
`[7.2,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9022-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9023-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9029-1	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-9039-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-9091-1	Linux kernel (NVIDIA Tegra) vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.179% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98900.mbox
https://git.kernel.org/stable/c/2299822f3f466b5dcad2377bf63986199f881a6b
https://git.kernel.org/stable/c/231542f4e43cf9837cb520664545e85fbe666b7b
https://git.kernel.org/stable/c/641de086a05f349de7fc548612432bc2fed721ca
https://git.kernel.org/stable/c/71a0cf87e19fb35c4292ca88985e376e613c900a
https://git.kernel.org/stable/c/720554c04acba80018ded069d3e0984bebaee891
https://git.kernel.org/stable/c/84d5727cef8eb9c8a28210ad248f1c70b223b065
https://git.kernel.org/stable/c/e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8
https://nvd.nist.gov/vuln/detail/CVE-2026-98900
https://www.cve.org/CVERecord?id=CVE-2026-98900

History

Oct 27, 2026 9:45 AM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses	CWE-20 CWE-400 CWE-680

Oct 27, 2026 4:30 AM Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-770
References		https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98900.mbox https://nvd.nist.gov/vuln/detail/CVE-2026-98900 https://www.cve.org/CVERecord?id=CVE-2026-98900
Metrics	threat_severity `None`	cvssV3_1 `{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Moderate`

Oct 23, 2026 3:30 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Linux linux
Vendors & Products		Linux linux

Oct 23, 2026 3:15 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-20 CWE-400 CWE-680

Oct 23, 2026 12:00 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		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.
Title		xen/gntalloc: validate grant count before allocation
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/2299822f3f466b5dcad2377bf63986199f881a6b https://git.kernel.org/stable/c/231542f4e43cf9837cb520664545e85fbe666b7b https://git.kernel.org/stable/c/641de086a05f349de7fc548612432bc2fed721ca https://git.kernel.org/stable/c/71a0cf87e19fb35c4292ca88985e376e613c900a https://git.kernel.org/stable/c/720554c04acba80018ded069d3e0984bebaee891 https://git.kernel.org/stable/c/84d5727cef8eb9c8a28210ad248f1c70b223b065 https://git.kernel.org/stable/c/e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8