How severe is CVE-2023-36849?

CVE-2023-36849 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2023-36849 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-36849?

CVE-2023-36849 primarily affects Juniper Junos. In total, 49 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-36849?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-36849 published?

CVE-2023-36849 was published on 2023-07-14 and last updated on 2026-06-17.

CVE-2023-36849

CVE-2023-36849 is a medium-severity vulnerability in Juniper Junos with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-703.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-703
Affected product: Juniper Junos
Published: 2023-07-14
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2023-36849?: 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.
How severe is CVE-2023-36849?: CVE-2023-36849 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2023-36849 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-36849?: CVE-2023-36849 primarily affects Juniper Junos. In total, 49 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-36849?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-36849 published?: CVE-2023-36849 was published on 2023-07-14 and last updated on 2026-06-17.

References

https://supportportal.juniper.net/JSA71660

Affected products (49)

cpe:2.3:o:juniper:junos:21.4:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r2-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r2-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r3:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r3-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:21.4:r3-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r2-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r2-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r3:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r3-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.1:r3-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.2:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.2:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.2:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.2:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.3:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.3:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:22.3:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r2-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r2-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r3:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:21.4:r3-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:22.1:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:22.1:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:22.1:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:22.1:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:22.1:r2-s1:*:*:*:*:*:*

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