CVE-2021-1368

Administrative code execution via malformed UDLD packets

Published Feb 24, 2021 · Updated Nov 8, 2024

Out-of-bounds write in Cisco NX-OS Software allows attackers to execute administrative code or reload devices via crafted UDLD packets. The UDLD packet-processing path insufficiently validates protocol fields, permitting malformed input to write beyond a buffer boundary. Exploitation requires control of a directly connected device and an affected port channel with UDLD enabled; additional system conditions enable code execution, while their absence causes repeated UDLD crashes and a device reload.

CVSS severity8.8
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Cisco NX-OS Software allows attackers to execute administrative code or reload devices via crafted UDLD packets. The UDLD packet-processing path insufficiently validates protocol fields, permitting malformed input to write beyond a buffer boundary. Exploitation requires control of a directly connected device and an affected port channel with UDLD enabled; additional system conditions enable code execution, while their absence causes repeated UDLD crashes and a device reload.

The record

CVE
CVE-2021-1368
Published
Feb 24, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco NX-OS Software
Classifications
CWE-787, T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 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 NX-OS Softwareversion=n/a

Published CVSS scores

8.8Cisco Systems, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
4.9NIST NVDAV:A/AC:M/Au:S/C:P/I:P/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-787Out-of-bounds Write
T1210Exploitation of Remote Services

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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