CVE-2023-36839

Junos OS and Junos OS Evolved: An l2cpd crash will occur when specific LLDP packets are received

MEDIUM

6.5

CVSS Score

Published: October 12, 2023 at 10:56 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 Validation of Specified Quantity in Input vulnerability in the Layer-2 control protocols daemon (l2cpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker who sends specific LLDP packets to cause a Denial of Service(DoS). This issue occurs when specific LLDP packets are received and telemetry polling is being done on the device. 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. This issue affects: Juniper Networks Junos OS * All versions prior to 20.4R3-S8; * 21.1 version 21.1R1 and later versions; * 21.2 versions prior to 21.2R3-S5; * 21.3 versions prior to 21.3R3-S4; * 21.4 versions prior to 21.4R3-S3; * 22.1 versions prior to 22.1R3-S2; * 22.2 versions prior to 22.2R3; * 22.3 versions prior to 22.3R2-S2; * 22.4 versions prior to 22.4R2; Juniper Networks Junos OS Evolved * All versions prior to 20.4R3-S8-EVO; * 21.1 version 21.1R1-EVO and later versions; * 21.2 versions prior to 21.2R3-S5-EVO; * 21.3 versions prior to 21.3R3-S4-EVO; * 21.4 versions prior to 21.4R3-S3-EVO; * 22.1 versions prior to 22.1R3-S2-EVO; * 22.2 versions prior to 22.2R3-EVO; * 22.3 versions prior to 22.3R2-S2-EVO; * 22.4 versions prior to 22.4R1-S1-EVO;

Affected

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

Junos OS Evolved · Juniper

95%

Affected range stops below 20.4, so it looks safe — our inference, not a vendor statement

Junos · Juniper Networks

95%

v < 20.4v < 20.4R3-S821.1R1 ≤ v < 21.1*21.2 ≤ v < 21.2R3-S521.3 ≤ v < 21.3R3-S421.4 ≤ v < 21.4R3-S322.1 ≤ v < 22.1R3-S222.2 ≤ v < 22.2R322.3 ≤ v < 22.3R2-S2, 22.3R322.4 ≤ v < 22.4R220.4 20.4 r1 20.4 r1-s1 20.4 r2 20.4 r2-s1 20.4 r2-s2 20.4 r3 20.4 r3-s1 20.4 r3-s2 20.4 r3-s3 20.4 r3-s4 20.4 r3-s5 20.4 r3-s6 20.4 r3-s7 21.1 r1 21.1 r1-s1 21.1 r2 21.1 r2-s1 21.1 r2-s2 21.1 r3 21.1 r3-s1 21.1 r3-s2 21.1 r3-s3 21.1 r3-s4 21.1 r3-s5 21.1R1 21.2 21.2 r1 21.2 r1-s1 21.2 r1-s2 21.2 r2 21.2 r2-s1 21.2 r2-s2 21.2 r3 21.2 r3-s1 21.2 r3-s2 21.2 r3-s3 21.2 r3-s4 21.3 21.3 r1 21.3 r1-s1 21.3 r1-s2 21.3 r2 21.3 r2-s1 21.3 r2-s2 21.3 r3 21.3 r3-s1 21.3 r3-s2 21.3 r3-s3 21.4 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 22.2 22.2 r1 22.2 r1-s1 22.2 r1-s2 22.2 r2 22.2 r2-s1 22.2 r2-s2 22.3 22.3 r1 22.3 r1-s1 22.3 r1-s2 22.3 r2 22.3 r2-s1 22.4 22.4 r1 22.4 r1-s1 22.4 r1-s2

Affected range stops below 20.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.4R3-S8, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.1*, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.2R3-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.3R3-S4, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 22.1R3-S2, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 22.3R2-S2, 22.3R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.4R2, so it looks safe — our inference, not a vendor statement

Junos OS Evolved · Juniper Networks

60%

v < 20.4R3-S8-EVO21.1R1-EVO ≤ v < 21.1*-EVO21.2-EVO ≤ v < 21.2R3-S5-EVO21.3-EVO ≤ v < 21.3R3-S4-EVO21.4-EVO ≤ v < 21.4R3-S3-EVO22.1-EVO ≤ v < 22.1R3-S2-EVO22.2-EVO ≤ v < 22.2R3-EVO22.3-EVO ≤ v < 22.3R2-S2-EVO, 22.3R3-EVO22.4-EVO ≤ v < 22.4R1-S1-EVO, 22.4R2-EVO21.1R1-EVO 21.2-EVO 21.3-EVO 21.4-EVO 22.1-EVO 22.2-EVO 22.3-EVO 22.4-EVO

Affected range stops below 20.4R3-S8-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.1*-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.2R3-S5-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.3R3-S4-EVO, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 22.1R3-S2-EVO, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 22.3R2-S2-EVO, 22.3R3-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.4R1-S1-EVO, 22.4R2-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/JSA73171

References (1)

Vendor Advisory

Source: [email protected]

https://supportportal.juniper.net/JSA73171

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-1284

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