What’s Vulnerable › Vulnerabilities
CVE-2026-57027: Junos OS: EX4100 Series, EX4400: With sFlow configured in a VC scenario multicast traffic leads to an FPC crash
- Severity: medium (CVSS 6.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-07-09 · updated 2026-10-25
- Weakness: CWE-401
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 products
- Juniper Junos OS: before 23.2; 23.2, 23.2-r1, 23.2-r1-s1, 23.2-r1-s2, 23.2-r2, 23.2-r2-s1 (+28) — fixed in 23.2
How to fix
Upgrade to a fixed version: Juniper Junos OS 23.2. Check the vendor advisory for mitigations.
References
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