CVE-2023-36849

Junos OS and Junos OS Evolved: The l2cpd will crash when a malformed LLDP packet is received

MEDIUM

6.5

CVSS Score

Published: July 14, 2023 at 05:58 PM UTC

Updated: June 17, 2026 at 06:07 AM UTC

3 products affected across 2 vendorsJunosJunos OS EvolvedJunos OS Evolved

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

An Improper Check or Handling of Exceptional Conditions vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a Denial of Service (DoS). When a malformed LLDP packet is received, l2cpd will crash and restart. The impact of the l2cpd crash is reinitialization of STP protocols (RSTP, MSTP or VSTP), and MVRP and ERP. Also, if any services depend on LLDP state (like PoE or VoIP device recognition), then these will also be affected. Continued receipt of such packets will lead to a sustained Denial of Service. This issue affects: Juniper Networks Junos OS 21.4 versions prior to 21.4R3-S3; 22.1 versions prior to 22.1R3-S3; 22.2 versions prior to 22.2R2-S1, 22.2R3; 22.3 versions prior to 22.3R2. Juniper Networks Junos OS Evolved 21.4-EVO versions prior to 21.4R3-S2-EVO; 22.1-EVO versions prior to 22.1R3-S3-EVO; 22.2-EVO versions prior to 22.2R2-S1-EVO, 22.2R3-EVO; 22.3-EVO versions prior to 22.3R2-EVO.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

21.4 ≤ v < 21.4R3-S322.1 ≤ v < 22.1R3-S322.2 ≤ v < 22.2R2-S1, 22.2R322.3 ≤ v < 22.3R221.4 21.4 r1 21.4 r1-s1 21.4 r1-s2 21.4 r2 21.4 r2-s1 21.4 r2-s2 21.4 r3 21.4 r3-s1 21.4 r3-s2 22.1 22.1 r1 22.1 r1-s1 22.1 r1-s2 22.1 r2 22.1 r2-s1 22.1 r2-s2 22.1 r3 22.1 r3-s1 22.1 r3-s2 22.2 22.2 r1 22.2 r1-s1 22.2 r1-s2 22.2 r2 22.3 22.3 r1 22.3 r1-s1 22.3 r1-s2

Affected range stops below 21.4R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.1R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.2R2-S1, 22.2R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.3R2, so it looks safe — our inference, not a vendor statement

Junos OS Evolved · Juniper Networks

60%

21.4 ≤ v < 21.4R3-S2-EVO22.1 ≤ v < 22.1R3-S3-EVO22.2 ≤ v < 22.2R2-S1-EVO, 22.2R3-EVO22.3 ≤ v < 22.3R2-EVO21.4 22.1 22.2 22.3

Affected range stops below 21.4R3-S2-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.1R3-S3-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.2R2-S1-EVO, 22.2R3-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.3R2-EVO, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://supportportal.juniper.net/JSA71660

References (1)

MitigationVendor Advisory

Source: [email protected]

https://supportportal.juniper.net/JSA71660

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMjuniper

Attack Vector: ADJACENT_NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-703

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