What is the CVSS score of CVE-2026-21911?

CVE-2026-21911 has a CVSS 3.1 base score of 6.5 (Medium). CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.0%.

Which versions of Junos Os Evolved are affected by CVE-2026-21911?

CVE-2026-21911 presents notable security risk rated CVSS 6.5. Exploitation could compromise the security of affected deployments.

Junos Os Evolved CVE-2026-21911

MEDIUM

Incorrect Calculation (CWE-682)

2026-01-15 sirt@juniper.net

Juniper Junos Os Evolved

6.5

CVSS 3.1

CVSS VectorNVD

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

CVE Published

Jan 15, 2026 - 21:16 nvd

MEDIUM 6.5

DescriptionNVD

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.

AnalysisAI

MAC learning failures in Juniper Junos OS Evolved's Layer 2 Control Protocol Daemon can be triggered by a network-adjacent attacker who repeatedly toggles the management interface, causing label-switched interface MAC address learning to halt while generating excessive logs and consuming high CPU resources. This calculation error (CWE-682) affects availability through denial of service and currently has no available patch. …

RemediationAI

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.

Analysis

Detailed AI-generated intelligence summary covering attack vector, impact assessment, affected versions, remediation steps, and indicators of compromise.

POChttps://••••••••••.com/exploit

PATCHhttps://••••••••••.com/patch

ADVISORYhttps://••••••••••.com/advisory