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CVE-2026-57027

Junos OS: EX4100 Series, EX4400: With sFlow configured in a VC scenario multicast traffic leads to an FPC crash

MEDIUM
6.5
CVSS Score
Published: July 9, 2026 at 09:08 PM UTC
Updated: October 25, 2026 at 03:10 PM UTC
1 product affected across 1 vendorJunos· also runs on 5 platforms

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

A Missing Release of Memory after Effective Lifetime vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX Series devices allows an unauthenticated adjacent attacker to cause a Denial-of-Service (DoS).When sFlow is configured in a Virtual Chassis (VC) scenario with EX4100 Series or EX4400 Series devices, multicast traffic which is received on one VC member and sent out on another member leads to a memory leak and ultimately an FPC crash and restart. The leak can be monitored by watching the continuous increase of the buffer values in the output of: user@host> show chassis fpc This issue affects Junos OS on EX4100 Series and EX4400: * all versions before 23.2R2-S7, * 23.4 versions before 23.4R2-S7, * 24.2 versions before 24.2R2-S4, * 24.4 versions before 24.4R2.

Affected

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

Junos· Juniper Networks
95%
v < 23.223.223.2 r123.2 r1-s123.2 r1-s223.2 r223.2 r2-s123.2 r2-s223.2 r2-s323.2 r2-s423.2 r2-s523.2 r2-s623.423.4 r123.4 r1-s123.4 r1-s223.4 r223.4 r2-s123.4 r2-s223.4 r2-s323.4 r2-s423.4 r2-s523.4 r2-s624.224.2 r124.2 r1-s124.2 r1-s224.2 r224.2 r2-s124.2 r2-s224.2 r2-s324.424.4 r124.4 r1-s224.4 r1-s3
Affected range stops below 23.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 23.2R2-S7, so it looks safe — our inference, not a vendor statement
Affected range stops below 23.4R2-S7, so it looks safe — our inference, not a vendor statement
Affected range stops below 24.2R2-S4, so it looks safe — our inference, not a vendor statement
Affected range stops below 24.4R2, so it looks safe — our inference, not a vendor statement
juniper-ex4100 (environment) · juniper-ex4100-f (environment) · juniper-ex4100-h (environment) · juniper-ex4100-h-12t (environment) · juniper-ex4400 (environment)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

Vendor Advisory
Source: cverecord
https://supportportal.juniper.net/JSA110087

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

StatusANALYZED
CWE
CWE-401

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