CVE Intelligence
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CVE-2026-89621 — HID: mcp2221: validate report size in mcp2221_raw_event()

In the Linux kernel, the following vulnerability has been resolved: HID: mcp2221: validate report size in mcp2221_raw_event() mcp2221_raw_event() never validates the size of incoming HID reports. In the MCP2221_I2C_GET_DATA path it trusts the device-supplied data[3] as the copy length without checking that 4 + data[3] bytes actually exist in the received report. A malicious or misbehaving USB device can send a short report with a large data[3], causing the memcpy to read past the valid report data in the HID transfer buffer and leak uninitialized kernel memory back to userspace through the I2C/SMBus read path. Add a minimum size check at entry and validate that the source range fits within the received report before the copy.

Published Sep 11, 2026 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · 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
  • EPSS 0.2% (30-day exploitation probability)+2

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
0.22%
ahead of 12% of scored CVEs · Oct 22, 2026
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 ≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < cb38b1f149b7143355b37e86c841acf0076e5c2a≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < b2c67dc0e30c308647bbd9b9e5d69a44c9d2733d≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < fffcfa367072628c3144cca17d2a3c3c9e50c057≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < c1c508e8923911cb458234997e55b7a4b9aa066f≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < bdc6a3af0dd734a326acdb7d6401a3b6a9f4f149≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < 127de5919820f88a9d55e8371ad4ac49f625f4c5≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < 7c18fb36708a97ff6772825cc087b6d537bbf0d5≥ 67a95c21463d066060b0f66d65a75d45bb386ffb and < 2c9a6998c19503626c57a2267bf279e204113079
and 1 more version 5.7
Vulnerable CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 22, 2026 · 7 reading(s) · max 0.22%

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 15, 2026
  • Affected products added · linux/linux
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Received
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 11, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 19, 2026 – Oct 19, 2026
  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

10 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 14h
  • CVE-2026-99087 dm-integrity: fix NULL pointer dereference when the 'R' flag is used 14h
  • CVE-2026-99079 net/mlx5e: Prevent stale XSK buffer release on refill retry 14h
  • CVE-2026-99080 fs: Free any excess xarray nodes in clear_inode() 14h
  • CVE-2026-99081 bnxt_en: fix DMA mapping length for padded small packets 14h
  • CVE-2026-99082 KVM: x86: Use active memslots for the per-vCPU MMIO cache 14h

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 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-2026-89621 is "HID: mcp2221: validate report size in mcp2221_raw_event()", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.22% estimates the probability of exploitation in 30 days; neither replaces your asset context. 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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