CVE-2021-47265

Local denial of service via unchecked RDMA port

Published May 21, 2024 · Updated May 11, 2026

Denial of service in Linux 3.12 through 5.12.10 allows local users to trigger a kernel oops through a crafted RDMA flow request. The ib_uverbs_ex_create_flow function passes the user-supplied flow port to the mlx5_ib driver without first calling rdma_is_port_valid. A local low-privileged account with access to RDMA user verbs is required; with panic-on-oops enabled, the resulting oops panics the host.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux 3.12 through 5.12.10 allows local users to trigger a kernel oops through a crafted RDMA flow request. The ib_uverbs_ex_create_flow function passes the user-supplied flow port to the mlx5_ib driver without first calling rdma_is_port_valid. A local low-privileged account with access to RDMA user verbs is required; with panic-on-oops enabled, the resulting oops panics the host.

The record

CVE
CVE-2021-47265
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=3.12
  2. Affected versionversion=436f2ad05a0b65b1467ddf51bc68171c381bf844 <2adcb4c5a52a2623cd2b43efa7041e74d19f3a5e
  3. Affected versionversion=436f2ad05a0b65b1467ddf51bc68171c381bf844 <8dc1b0e0ca204596c50bcd159ee069ae0f998176

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.12; version=436f2ad05a0b65b1467ddf51bc68171c381bf844 <2adcb4c5a52a2623cd2b43efa7041e74d19f3a5e; version=436f2ad05a0b65b1467ddf51bc68171c381bf844 <8dc1b0e0ca204596c50bcd159ee069ae0f998176

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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.

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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

T1499.004Application or System Exploitation

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

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Your stack

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