CVE-2021-47080

Kernel crash via zero RDMA entry size

Published Mar 1, 2024 · Updated May 11, 2026

Divide by zero in the Linux kernel RDMA core allows local users to crash the kernel through a crafted query-GID-table ioctl. ib_uverbs_handler_UVERBS_METHOD_QUERY_GID_TABLE uses the user-supplied user_entry_size as a divisor without rejecting zero. A low-privileged local user with access to the RDMA userspace verbs interface can trigger a divide error and interrupt the host.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Divide by zero in the Linux kernel RDMA core allows local users to crash the kernel through a crafted query-GID-table ioctl. ib_uverbs_handler_UVERBS_METHOD_QUERY_GID_TABLE uses the user-supplied user_entry_size as a divisor without rejecting zero. A low-privileged local user with access to the RDMA userspace verbs interface can trigger a divide error and interrupt the host.

The record

CVE
CVE-2021-47080
Published
Mar 1, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-369
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 1, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.10
  2. Affected versionversion=9f85cbe50aa044a46f0a22fda323fa27b80c82da <54d87913f147a983589923c7f651f97de9af5be1
  3. Affected versionversion=9f85cbe50aa044a46f0a22fda323fa27b80c82da <66ab7fcdac34b890017f04f391507ef5b2b89a13
  4. Affected versionversion=9f85cbe50aa044a46f0a22fda323fa27b80c82da <e6871b4270c05f8b212e7d98aee82b357972c80a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10; version=9f85cbe50aa044a46f0a22fda323fa27b80c82da <54d87913f147a983589923c7f651f97de9af5be1; version=9f85cbe50aa044a46f0a22fda323fa27b80c82da <66ab7fcdac34b890017f04f391507ef5b2b89a13; version=9f85cbe50aa044a46f0a22fda323fa27b80c82da <e6871b4270c05f8b212e7d98aee82b357972c80a

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.4Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-369Divide By Zero

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo