CVE-2021-20988Network attack vector

Service interruption via unchecked UDP packet length

Published May 13, 2021 · Updated Sep 16, 2024

Memory-boundary flaw in Hilscher rcX RTOS before 2.1.14.1 allows remote attackers to interrupt devices via crafted UDP packets. The UDP receive path trusts the length declared in a packet without checking it against the datagram's actual length, allowing processing beyond the received buffer. No authentication or user interaction is required; a crafted network packet can interrupt the embedded device, while published impact is limited to availability.

CVSS severity8.6
High
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory-boundary flaw in Hilscher rcX RTOS before 2.1.14.1 allows remote attackers to interrupt devices via crafted UDP packets. The UDP receive path trusts the length declared in a packet without checking it against the datagram's actual length, allowing processing beyond the received buffer. No authentication or user interaction is required; a crafted network packet can interrupt the embedded device, while published impact is limited to availability.

The record

CVE
CVE-2021-20988
Published
May 13, 2021
Updated
Sep 16, 2024
Vendor
Hilscher
Product
rcX RTOS
Classifications
CWE-119, T1498
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record 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=unspecified <V2.1.14.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hilscher · rcX RTOSversion=unspecified <V2.1.14.1

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
8.6CERT VDECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1498Network Denial of Service

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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