CVE-2026-57027: CWE-401 Missing Release of Memory after Effective Lifetime in Juniper Networks Junos OS
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.
AI Analysis
Technical Summary
CVE-2026-57027 is a CWE-401 vulnerability involving a missing release of memory after its effective lifetime in the packet forwarding engine of Juniper Networks Junos OS on EX4100 and EX4400 Series devices. When sFlow is enabled in a Virtual Chassis configuration, multicast traffic forwarded between members causes a memory leak that accumulates over time, observable via increasing buffer values in 'show chassis fpc' output. This leak ultimately results in an FPC crash and restart, causing a denial-of-service condition. The vulnerability affects all versions before 23.2R2-S7, 23.4 versions before 23.4R2-S7, 24.2 versions before 24.2R2-S4, and 24.4 versions before 24.4R2.
Potential Impact
An unauthenticated adjacent attacker can trigger a denial-of-service by exploiting the memory leak caused by multicast traffic in a Virtual Chassis scenario with sFlow configured. The impact is limited to causing an FPC crash and restart, disrupting device operation and network availability. There is no impact on confidentiality or integrity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The vulnerability affects versions prior to 23.2R2-S7, 23.4R2-S7, 24.2R2-S4, and 24.4R2. Users should monitor Juniper Networks advisories for official fixes and apply updates once available. Until patched, consider disabling sFlow in Virtual Chassis configurations on affected devices if feasible to mitigate the risk.
CVE-2026-57027: CWE-401 Missing Release of Memory after Effective Lifetime in Juniper Networks Junos OS
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.
CVSS v3.1
Score 6.5medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-57027 is a CWE-401 vulnerability involving a missing release of memory after its effective lifetime in the packet forwarding engine of Juniper Networks Junos OS on EX4100 and EX4400 Series devices. When sFlow is enabled in a Virtual Chassis configuration, multicast traffic forwarded between members causes a memory leak that accumulates over time, observable via increasing buffer values in 'show chassis fpc' output. This leak ultimately results in an FPC crash and restart, causing a denial-of-service condition. The vulnerability affects all versions before 23.2R2-S7, 23.4 versions before 23.4R2-S7, 24.2 versions before 24.2R2-S4, and 24.4 versions before 24.4R2.
Potential Impact
An unauthenticated adjacent attacker can trigger a denial-of-service by exploiting the memory leak caused by multicast traffic in a Virtual Chassis scenario with sFlow configured. The impact is limited to causing an FPC crash and restart, disrupting device operation and network availability. There is no impact on confidentiality or integrity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The vulnerability affects versions prior to 23.2R2-S7, 23.4R2-S7, 24.2R2-S4, and 24.4R2. Users should monitor Juniper Networks advisories for official fixes and apply updates once available. Until patched, consider disabling sFlow in Virtual Chassis configurations on affected devices if feasible to mitigate the risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- juniper
- Date Reserved
- 2026-06-23T16:27:00.248Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a50171668715ace431ea202
Added to database: 07/09/2026, 21:48:06 UTC
Last enriched: 07/17/2026, 09:55:06 UTC
Last updated: 08/22/2026, 22:52:14 UTC
Views: 66
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