CVE-2021-27427Network attack vector

Code execution via unchecked calloc multiplication

Published May 3, 2022 · Updated Apr 16, 2025

Integer overflow in calloc in RIOT OS 2020.01.1 allows remote attackers to crash devices or execute code through crafted allocations. Its calloc implementation multiplies the element count by element size without checking for wraparound, then allocates the resulting undersized buffer. Exploitation requires control of both calloc arguments and subsequent memory accesses; resulting memory corruption can crash the device or execute injected code.

CVSS severity7.3
High
EPSS probability1.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in calloc in RIOT OS 2020.01.1 allows remote attackers to crash devices or execute code through crafted allocations. Its calloc implementation multiplies the element count by element size without checking for wraparound, then allocates the resulting undersized buffer. Exploitation requires control of both calloc arguments and subsequent memory accesses; resulting memory corruption can crash the device or execute injected code.

The record

CVE
CVE-2021-27427
Published
May 3, 2022
Updated
Apr 16, 2025
Vendor
RIOT-OS
Product
RIOT OS
Classifications
CWE-190, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 3, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 2025Record 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=2020.01.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

RIOT-OS · RIOT OSversion=2020.01.1

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3ICS-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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