CVE-2026-57019

Traffic interruption via incorrect packet-size calculation

Published Jul 9, 2026 · Updated Jul 9, 2026

Improper packet-size validation in Juniper Networks Junos OS on MX Series allows attackers to interrupt traffic with a crafted packet. The Packet Forwarding Engine calculates the packet size incorrectly, so later processing raises a major error and resets the Flexible PIC Concentrator. The packet must arrive from the same broadcast domain during MAP-T or IP-encapsulated non-IP traffic, and the reset interrupts traffic only until automatic recovery.

CVSS severity7.1
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper packet-size validation in Juniper Networks Junos OS on MX Series allows attackers to interrupt traffic with a crafted packet. The Packet Forwarding Engine calculates the packet size incorrectly, so later processing raises a major error and resets the Flexible PIC Concentrator. The packet must arrive from the same broadcast domain during MAP-T or IP-encapsulated non-IP traffic, and the reset interrupts traffic only until automatic recovery.

The record

CVE
CVE-2026-57019
Published
Jul 9, 2026
Updated
Jul 9, 2026
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-1284, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <23.2R2-S6
  2. Affected versionversion=23.4 <23.4R2-S7
  3. Affected versionversion=24.2 <24.2R2-S4
  4. Affected versionversion=24.4 <24.4R2-S4
  5. Affected versionversion=25.2 <25.2R2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <23.2R2-S6; version=23.4 <23.4R2-S7; version=24.2 <24.2R2-S4; version=24.4 <24.4R2-S4; version=25.2 <25.2R2

Published CVSS scores

6.5Juniper NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.1Juniper NetworksCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1284Improper Validation of Specified Quantity in Input
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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