Answer in brief
CVE-2026-57019 records a Medium severity (CVSS 6.5) vulnerability in Junos OS: MX Series: Specific traffic causes an FPC to reset. The current sources do not mark it as known exploited. The current feed maps Juniper Networks/Junos OS (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Juniper Networks/Junos OS (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Juniper Networks/Junos OSgeneric | >=0 <23.2R2-S6 || >=23.4 <23.4R2-S7 || >=24.2 <24.2R2-S4 || >=24.4 <24.4R2-S4 || >=25.2 <25.2R2 | 23.2R2-S6, 23.4R2-S7, 24.2R2-S4, 24.4R2-S4, 25.2R2 |
Published upstream
Jul 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 10, 2026
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). 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. Affected scenarios are: MAP-T, or non-IP traffic encapsulated in IP (e.g. MPLS over GRE). When this issue happens the following logs can be observed: 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 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 This issue affects Junos OS on MX Series: * all versions before 23.2R2-S6, * 23.4 versions before 23.4R2-S7, * 24.2 versions before 24.2R2-S4, * 24.4 versions before 24.4R2-S4, * 25.2 versions before 25.2R2.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-57019 records a Medium severity (CVSS 6.5) vulnerability in Junos OS: MX Series: Specific traffic causes an FPC to reset. The current sources do not mark it as known exploited. The current feed maps Juniper Networks/Junos OS (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Juniper Networks/Junos OS (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Juniper Networks/Junos OSgeneric | >=0 <23.2R2-S6 || >=23.4 <23.4R2-S7 || >=24.2 <24.2R2-S4 || >=24.4 <24.4R2-S4 || >=25.2 <25.2R2 | 23.2R2-S6, 23.4R2-S7, 24.2R2-S4, 24.4R2-S4, 25.2R2 |
Published upstream
Jul 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 10, 2026
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). 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. Affected scenarios are: MAP-T, or non-IP traffic encapsulated in IP (e.g. MPLS over GRE). When this issue happens the following logs can be observed: 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 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 This issue affects Junos OS on MX Series: * all versions before 23.2R2-S6, * 23.4 versions before 23.4R2-S7, * 24.2 versions before 24.2R2-S4, * 24.4 versions before 24.4R2-S4, * 25.2 versions before 25.2R2.
Quoted source text, attributed separately from HOL analysis.