CVE-2021-21282Public exploitNetwork attack vector

Memory corruption via unchecked source-routing segment count

Published Jun 18, 2021 · Updated Aug 3, 2024

Buffer overflow in Contiki-NG before 4.5 allows remote attackers to corrupt memory via a crafted RPL source-routing packet. In both rpl-ext-header.c implementations, an unchecked segments_left value can exceed the attacker-influenced path_len, wrapping the next-address index so memcpy accesses beyond the packet buffer. The packet is reachable without authentication only in source-routing mode; the advisory does not specify whether corruption causes a crash or code execution.

CVSS severity9.8
Critical
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

Buffer overflow in Contiki-NG before 4.5 allows remote attackers to corrupt memory via a crafted RPL source-routing packet. In both rpl-ext-header.c implementations, an unchecked segments_left value can exceed the attacker-influenced path_len, wrapping the next-address index so memcpy accesses beyond the packet buffer. The packet is reachable without authentication only in source-routing mode; the advisory does not specify whether corruption causes a crash or code execution.

The record

CVE
CVE-2021-21282
Published
Jun 18, 2021
Updated
Aug 3, 2024
Vendor
Contiki-NG
Product
Contiki-NG
Classifications
CWE-120
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 4.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Contiki-NG · Contiki-NGversion=< 4.5

Published CVSS scores

7.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/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 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 exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Public exploit references

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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