CVE-2021-43612Network attack vector

Parser crash via undersized SONMP length check

Published Apr 15, 2023 · Updated Feb 13, 2025

Out-of-bounds heap read in lldpd before 1.0.13 allows remote attackers to crash the SONMP parser with a short SONMP packet. The sonmp_decode function checked the frame against an undersized SONMP_SIZE value, then consumed address and header fields beyond the heap allocation. A device able to send SONMP traffic can interrupt only the unprivileged, chrooted parser process; upstream reports no arbitrary code execution.

CVSS severity7.5
High
EPSS probability1.14%
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 heap read in lldpd before 1.0.13 allows remote attackers to crash the SONMP parser with a short SONMP packet. The sonmp_decode function checked the frame against an undersized SONMP_SIZE value, then consumed address and header fields beyond the heap allocation. A device able to send SONMP traffic can interrupt only the unprivileged, chrooted parser process; upstream reports no arbitrary code execution.

The record

CVE
CVE-2021-43612
Published
Apr 15, 2023
Updated
Feb 13, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.

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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-787Out-of-bounds Write
T1499.004Application or System Exploitation

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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