← Vulnerability feed

Vulnerability record · CVE-2026-33780 · published 9 April 2026

CVE-2026-33780: Juniper junos memory leak vulnerability

Juniper · Junos

A Missing Release of Memory after Effective Lifetime vulnerability in the Layer 2 Address Learning Daemon (l2ald) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause a memory leak ultimately leading to a Denial of Service (DoS). In an EVPN-MPLS scenario, routes learned from remote multi-homed Provider Edge (PE) devices are programmed as ESI routes. Due to a logic issue in the l2ald memory management, memory allocated for these routes is not released when there is churn for these routes. As a result, memory leaks in the l2ald process which will ultimately lead to a crash and restart of l2ald. Use the following command to monitor the memory consumption by l2ald: user@device> show system process extensive | match "PID|l2ald" This issue affects: Junos OS: * all versions before 22.4R3-S5, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R2; Junos OS Evolved: * all versions before 22.4R3-S5-EVO, * 23.2 versions before 23.2R2-S3-EVO, * 23.4 versions before 23.4R2-S4-EVO, * 24.2 versions before 24.2R2-EVO.

7.1 CVSS 4.0 High EPSS 0.28% · top 81.6% CWE-401 · Memory leak
7.1CVSS 4.0 base score
0.28%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
1References
17 Jun 2026Last modified by NVD

Description

A Missing Release of Memory after Effective Lifetime vulnerability in the Layer 2 Address Learning Daemon (l2ald) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause a memory leak ultimately leading to a Denial of Service (DoS). In an EVPN-MPLS scenario, routes learned from remote multi-homed Provider Edge (PE) devices are programmed as ESI routes. Due to a logic issue in the l2ald memory management, memory allocated for these routes is not released when there is churn for these routes. As a result, memory leaks in the l2ald process which will ultimately lead to a crash and restart of l2ald. Use the following command to monitor the memory consumption by l2ald: user@device> show system process extensive | match "PID|l2ald" This issue affects: Junos OS: * all versions before 22.4R3-S5, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R2; Junos OS Evolved: * all versions before 22.4R3-S5-EVO, * 23.2 versions before 23.2R2-S3-EVO, * 23.4 versions before 23.4R2-S4-EVO, * 24.2 versions before 24.2R2-EVO.

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/JSA107819 Vendor Advisory

Track CVE-2026-33780 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

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-2026-33780), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.