VulnerabilityPublished 23 Oct 2026Updated 26 Oct 2026

CVE-2026-98900: Linux kernel · xen/gntalloc: validate grant count before allocation

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:07 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8, 2299822f3f466b5dcad2377bf63986199f881a6b, 720554c04acba80018ded069d3e0984bebaee891 +4

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ dd3140588d9551235ebc2a0dacdca098e7677573, < e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8	Fixed in e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8
LinuxLinux	Affected ≥ dd3140588d9551235ebc2a0dacdca098e7677573, < 2299822f3f466b5dcad2377bf63986199f881a6b	Fixed in 2299822f3f466b5dcad2377bf63986199f881a6b
LinuxLinux	Affected ≥ dd3140588d9551235ebc2a0dacdca098e7677573, < 720554c04acba80018ded069d3e0984bebaee891	Fixed in 720554c04acba80018ded069d3e0984bebaee891
LinuxLinux	Affected ≥ dd3140588d9551235ebc2a0dacdca098e7677573, < 231542f4e43cf9837cb520664545e85fbe666b7b	Fixed in 231542f4e43cf9837cb520664545e85fbe666b7b
LinuxLinux	Affected ≥ dd3140588d9551235ebc2a0dacdca098e7677573, < 641de086a05f349de7fc548612432bc2fed721ca	Fixed in 641de086a05f349de7fc548612432bc2fed721ca
LinuxLinux	Affected ≥ dd3140588d9551235ebc2a0dacdca098e7677573, < 84d5727cef8eb9c8a28210ad248f1c70b223b065	Fixed in 84d5727cef8eb9c8a28210ad248f1c70b223b065

AI-suggested

A fix is available and has been applied in the Linux kernel. Users should upgrade to a kernel version that includes the commits identified as fixes (e.g., those referenced by the provided commit hashes).

Description

A vulnerability in the Linux kernel's xen/gntalloc component was fixed by validating the grant count before allocation. The flaw involved allocating a grant-id array without first ensuring the requested count was within the global grant limit, potentially leading to improper memory allocation. The fix adds a subtraction-based check under a mutex to prevent integer wraparound and ensures 64-bit arithmetic is used for size calculations.

Impact

Improper validation of the grant count before allocation could lead to memory allocation errors or resource mismanagement in the kernel's grant allocation mechanism. This may affect system stability or security depending on how the grant allocations are used, but no explicit exploitation or impact details are provided.

Summary

The Linux kernel's xen/gntalloc interface had a vulnerability where gntalloc_ioctl_alloc() allocated memory for grant IDs before verifying that the requested count did not exceed the global grant limit. This could cause user-controlled allocations to proceed even when the count was too large, potentially leading to memory allocation issues. The patch introduces a subtraction-based validation while holding gref_mutex to prevent wraparound when adding the requested count. Additionally, it casts the count to 64-bit before advancing the per-file index to ensure correct page-size multiplication arithmetic.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:33 UTC

Technical details

References

Community reviews

Related threats