CVE Intelligence
Unknown

CVE-2026-98900 — xen/gntalloc: validate grant count before allocation

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.

Published Oct 23, 2026 · Updated Oct 23, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • No scoring signals.

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
—
No EPSS score.
Affects
Linux
Linux
CVSS base
—
Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 71a0cf87e19fb35c4292ca88985e376e613c900a≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 641de086a05f349de7fc548612432bc2fed721ca≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 720554c04acba80018ded069d3e0984bebaee891≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 84d5727cef8eb9c8a28210ad248f1c70b223b065≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 231542f4e43cf9837cb520664545e85fbe666b7b≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 2299822f3f466b5dcad2377bf63986199f881a6b< 5.10.271
and 6 more < 5.15.222< 6.1.189< 6.6.158< 6.12.111< 6.18.53versions not specified by the source
Vulnerable CVE Program (cve.org) e CISA ADP

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Not enough vector or weakness data: use the affected application’s logs as a starting point.
application logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Record published
    Oct 23, 2026
  • Affected products added · linux/linux
    Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Received
    Oct 23, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 23, 2026 · Alertas do Telegram
  • CVE published
    Oct 23, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 23, 2026 – Oct 23, 2026
  • 1× Official description updated · Oct 23, 2026 – Oct 23, 2026

References

7 on the record

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

  • CVE-2026-99086 dm-integrity: validate the superblock on resume 1d
  • CVE-2026-99087 dm-integrity: fix NULL pointer dereference when the 'R' flag is used 1d
  • CVE-2026-99080 fs: Free any excess xarray nodes in clear_inode() 1d
  • CVE-2026-99084 readdir: take no inode lock on an immutable directory 1d
  • CVE-2026-99085 sched_ext: Fix CPU hotplug hang when a dying CPU's tasks sit in the BPF scheduler 1d
  • CVE-2026-99079 net/mlx5e: Prevent stale XSK buffer release on refill retry 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CVSS score published by NVD, the CNA, CISA or GitHub so far.
  • No FIRST EPSS score.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No CWE classification.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-98900 is "xen/gntalloc: validate grant count before allocation", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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