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Vulnerability record · CVE-2026-33797 · published 9 April 2026

CVE-2026-33797: Juniper junos improper input validation vulnerability

Juniper · Junos

An Improper Input Validation vulnerability in Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, adjacent attacker, sending a specific genuine BGP packet in an already established BGP session to reset only that session causing a Denial of Service (DoS). An attacker repeatedly sending the packet will sustain the Denial of Service (DoS).This issue affects Junos OS: * 25.2 versions before 25.2R2 This issue does not affect Junos OS versions before 25.2R1. This issue affects Junos OS Evolved: * 25.2-EVO versions before 25.2R2-EVO This issue does not affect Junos OS Evolved versions before 25.2R1-EVO. eBGP and iBGP are affected. IPv4 and IPv6 are affected.

7.1 CVSS 4.0 High EPSS 0.27% · top 82.9% CWE-20 · Improper input validation
7.1CVSS 4.0 base score
0.27%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

An Improper Input Validation vulnerability in Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, adjacent attacker, sending a specific genuine BGP packet in an already established BGP session to reset only that session causing a Denial of Service (DoS). An attacker repeatedly sending the packet will sustain the Denial of Service (DoS).This issue affects Junos OS: * 25.2 versions before 25.2R2 This issue does not affect Junos OS versions before 25.2R1. This issue affects Junos OS Evolved: * 25.2-EVO versions before 25.2R2-EVO This issue does not affect Junos OS Evolved versions before 25.2R1-EVO. eBGP and iBGP are affected. IPv4 and IPv6 are affected.

CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://kb.juniper.net/JSA107850 Vendor Advisory
https://supportportal.juniper.net/JSA107850

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2023-36845Juniper Junos OS J-Web PHP variable modification RCEJ-Web in Junos OS on EX Series and SRX Series mishandles the PHP PHPRC environment variable, letting a crafted request alter the PHP execution enviro…KEVEPSS 95%analysed9.8CVE-2020-1631Juniper Junos OS J-Web HTTP service path traversal and local file inclusionThe HTTP/HTTPS service behind J-Web, Web Authentication, Dynamic-VPN, Firewall Authentication Pass-Through with Web-Redirect, and ZTP in Junos OS doe…KEVEPSS 4.8%analysed6.7CVE-2025-21590Juniper Junos OS kernel improper isolation allows local code injectionJunos OS contains an improper isolation or compartmentalization flaw in the kernel that lets a local attacker with shell access inject arbitrary code…KEVEPSS 1.7%analysed5.3CVE-2023-36851Juniper Junos OS SRX J-Web missing authentication allows file upload/downloadJunos OS on SRX Series exposes webauth_operation.php without authentication, letting a network attacker upload and download arbitrary files through J…KEVEPSS 1.1%analysed5.3CVE-2023-36844Juniper Junos OS EX Series J-Web PHP Environment Variable ModificationJ-Web on Junos OS for EX Series fails to properly restrict external PHP variable modification, letting an unauthenticated network attacker alter impo…KEVEPSS 90%analysed5.3CVE-2023-36846Juniper Junos OS SRX J-Web Missing Authentication Allows File UploadJunos OS on SRX Series fails to require authentication for a critical function in user.php reachable through J-Web, letting an unauthenticated networ…KEVEPSS 93%analysed5.3CVE-2023-36847Juniper Junos OS EX Series J-Web installAppPackage.php missing authenticationJunos OS on EX Series exposes installAppPackage.php through J-Web without requiring authentication. An unauthenticated network attacker can upload ar…KEVEPSS 83%analysed10.0CVE-2021-31384Juniper junos improper authorization vulnerabilityDue to a Missing Authorization weakness and Insufficient Granularity of Access Control in a specific device configuration, a vulnerability exists in …EPSS 1.2%

Source: NIST National Vulnerability Database (record CVE-2026-33797), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.