CVE-2026-57019
Severity CVSS v4.0:
HIGH
Type:
Unavailable / Other
Publication date:
09/07/2026
Last modified:
09/07/2026
Description
An Improper Validation of Specified Quantity in Input vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS).<br />
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When a specific packet is received from device in the same broadcast domain, an affected system calculates the packet size incorrectly. This causes further packet processing to fail, which triggers an FPC major error, resulting in a FPC reset impacting traffic until the FPC has automatically recovered.<br />
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Affected scenarios are: MAP-T, or non-IP traffic encapsulated in IP (e.g. MPLS over GRE).<br />
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When this issue happens the following logs can be observed:<br />
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fpc CMError: /fpc/0/pfe/0/cm/0/MQSS(0)/0/MQSS_CMERROR_LI_INT_REG_UNROLL_TAIL_LENGTH_OVF (0x2205eb), scope: pfe, category: functional, severity: major, module: MQSS(0), type: LI: Unroll TAIL length overflow, oc_category: default<br />
fpc Performing action reset-fru for error /fpc/0/pfe/0/cm/0/MQSS(0)/0/MQSS_CMERROR_LI_INT_REG_UNROLL_TAIL_LENGTH_OVF (0x2205eb) in module: MQSS(0) with scope: pfe category: functional level: major, oc_category: default<br />
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This issue affects Junos OS on MX Series:<br />
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* all versions before 23.2R2-S6,<br />
* 23.4 versions before 23.4R2-S7,<br />
* 24.2 versions before 24.2R2-S4,<br />
* 24.4 versions before 24.4R2-S4,<br />
* 25.2 versions before 25.2R2.
Impact
Base Score 4.0
7.10
Severity 4.0
HIGH
Base Score 3.x
6.50
Severity 3.x
MEDIUM