CVE-2021-1352

Device reload via malformed DECnet traffic

Published Mar 24, 2021 · Updated Nov 8, 2024

Improper input validation in Cisco IOS XE Software allows attackers to reload devices by sending crafted DECnet traffic. The DECnet Phase IV and DECnet/OSI protocol processors fail to validate packet-derived pointer offsets before memory access. Exposure requires a vulnerable IOS XE release with DECnet enabled on an interface; DECnet is disabled by default, and exploitation reloads the device.

CVSS severity7.4
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Cisco IOS XE Software allows attackers to reload devices by sending crafted DECnet traffic. The DECnet Phase IV and DECnet/OSI protocol processors fail to validate packet-derived pointer offsets before memory access. Exposure requires a vulnerable IOS XE release with DECnet enabled on an interface; DECnet is disabled by default, and exploitation reloads the device.

The record

CVE
CVE-2021-1352
Published
Mar 24, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-823, CWE-119, CAPEC-129, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 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?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XE Softwareversion=n/a

Published CVSS scores

7.4Cisco Systems, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
6.5NIST National Vulnerability DatabaseCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
2.9NIST National Vulnerability DatabaseAV:A/AC:M/Au:N/C:N/I:N/A:P

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-823Use of Out-of-range Pointer Offset
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CAPEC-129Pointer Manipulation
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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