CVE-2026-89621: Linux kernel · HID: mcp2221: validate report size in mcp2221_raw_event()
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 17:16 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 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.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available that adds proper validation of the HID report size in the mcp2221_raw_event() function. Users should update to a Linux kernel version that includes this patch. Since this is a kernel vulnerability, applying the official kernel update from the vendor or distribution is the recommended remediation.
Description
A vulnerability in the Linux kernel's HID driver for the MCP2221 device allows a malicious or faulty USB device to cause a buffer over-read by sending a crafted HID report with an invalid size. This leads to leaking uninitialized kernel memory to userspace via the I2C/SMBus read path. The issue is due to lack of validation of the report size in the mcp2221_raw_event() function. The vulnerability affects specific Linux kernel versions and has been resolved by adding proper size validation checks.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89621 (opens in a new tab)
- git.kernel.org/stable/c/127de5919820f88a9d55e8371ad4ac49f625f4c5 (opens in a new tab)
- git.kernel.org/stable/c/2c9a6998c19503626c57a2267bf279e204113079 (opens in a new tab)
- git.kernel.org/stable/c/7c18fb36708a97ff6772825cc087b6d537bbf0d5 (opens in a new tab)
- git.kernel.org/stable/c/bdc6a3af0dd734a326acdb7d6401a3b6a9f4f149 (opens in a new tab)
- ubuntu.com/security/CVE-2026-89621 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89621 (opens in a new tab)
- git.kernel.org/linus/2c9a6998c19503626c57a2267bf279e204113079 (opens in a new tab)