Vulnerability Monitor

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CVE-2026-21911

An Incorrect Calculation vulnerability in the Layer 2 Control Protocol Daemon (l2cpd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-adjacent attacker flapping the management interface to cause the learning of new MACs over label-switched interfaces (LSI) to stop while generating a flood of logs, resulting in high CPU usage. When the issue is seen, the following log message will be generated: op:1 flag:0x6 mac:xx:xx:xx:xx:xx:xx bd:2 ifl:13302 reason:0(REASON_NONE) i-op:6(INTRNL_OP_HW_FORCE_DELETE) status:10 lstatus:10 err:26(GETIFBD_VALIDATE_FAILED) err-reason 4(IFBD_VALIDATE_FAIL_EPOCH_MISMATCH) hw_wr:0x4 ctxsync:0 fwdsync:0 rtt-id:51 p_ifl:0 fwd_nh:0 svlbnh:0 event:- smask:0x100000000 dmask:0x0 mplsmask 0x1 act:0x5800 extf:0x0 pfe-id 0 hw-notif-ifl 13302 programmed-ifl 4294967295 pseudo-vtep underlay-ifl-idx 0 stack:GET_MAC, ALLOCATE_MAC, GET_IFL, GET_IFF, GET_IFBD, STOP, This issue affects Junos OS Evolved:  * all versions before 21.4R3-S7-EVO,  * from 22.2 before 22.2R3-S4-EVO,  * from 22.3 before 22.3R3-S3-EVO,  * from 22.4 before 22.4R3-S2-EVO,  * from 23.2 before 23.2R2-S1-EVO,  * from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.

Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.5, indicating it requires adjacent network access with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 1 product from juniper organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2026-01-15T21:16:07.110

Last Modified

2026-01-23T16:59:03.777

Status

Analyzed

Source

[email protected]

Severity

CVSSv3.1: 6.5 (MEDIUM)

Weaknesses
  • Type: Primary
    CWE-682
Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System juniper junos_os_evolved < 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 21.4 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.2 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.3 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 22.4 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.2 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
Operating System juniper junos_os_evolved 23.4 Yes
References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For juniper's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.