CVE-2021-32771Network attack vector

Unauthenticated memory corruption via unchecked DAO prefix length

Published Aug 4, 2022 · Updated Apr 23, 2025

Buffer overflow in Contiki-NG before 4.8 allows remote attackers to corrupt memory via a crafted RPL-Classic DAO packet. In dao_input_storing and dao_input_nonstoring, rpl-icmp6.c copies a packet-controlled IPv6 prefix into a 128-bit stack buffer without bounding its prefix length or confirming that the packet contains the declared bytes. Reachability requires the node to have joined an RPL DODAG; an oversized Target option causes an out-of-bounds write and can also over-read the packet, while no specific post-corruption outcome is published.

CVSS severity8.1
High
EPSS probability1.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in Contiki-NG before 4.8 allows remote attackers to corrupt memory via a crafted RPL-Classic DAO packet. In dao_input_storing and dao_input_nonstoring, rpl-icmp6.c copies a packet-controlled IPv6 prefix into a 128-bit stack buffer without bounding its prefix length or confirming that the packet contains the declared bytes. Reachability requires the node to have joined an RPL DODAG; an oversized Target option causes an out-of-bounds write and can also over-read the packet, while no specific post-corruption outcome is published.

The record

CVE
CVE-2021-32771
Published
Aug 4, 2022
Updated
Apr 23, 2025
Vendor
Contiki-NG
Product
Contiki-NG
Classifications
CWE-126, CWE-121, CWE-120
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 4, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 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=< 4.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Contiki-NG · Contiki-NGversion=< 4.8

Published CVSS scores

8.1NISTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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-126Buffer Over-read
CWE-121Stack-based Buffer Overflow
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

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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