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01 Record

CVE-2026-21911

Junos OS Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop

HighPUBLISHEDCNA: juniper
CNA base score7.1 CVSS v4.0CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Amber

02 Description

Junos OS Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.23% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 14.7% of scored records. A rank, not a probability.
NVD base score
7.1 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:C/RE:M/U:Amber
NVD analysis status
Analyzed. NVD last modified this record on 2026-06-17.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-01-15 20:23Z9 MO AGO
Last updated
2026-01-15 20:51Z9 MO AGO
Reserved
2026-01-05
Assigning CNA
juniper
Record state
PUBLISHED
Severity
High (CVSS 7.1)
CNA CVSS vector
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Amber
Weaknesses
Data version
5.2
Document digest
3cd680d52f46b26331d3d6e58e91c55e065a4b52bd150d5a8f3840ad49e159bb

05 Affected products

VendorProductVersionsPlatforms
Juniper NetworksJunos OS Evolved0 to < 21.4R3-S7-EVO, 22.2 to < 22.2R3-S4-EVO, 22.3 to < 22.3R3-S3-EVO, 22.4 to < 22.4R3-S2-EVO, 23.2 to < 23.2R2-S1-EVO, 23.4 to < 23.4R1-S2-EVO, 23.4R2-EVO—

06 References

07 Remediation

The following software releases have been updated to resolve this specific issue: 21.4R3-S7-EVO, 22.2R3-S4-EVO, 22.3R3-S3-EVO, 22.4R3-S2-EVO, 23.2R2-S1-EVO, 23.4R1-S2-EVO, 23.4R2-EVO, 24.2R1-EVO, and all subsequent releases.