Vulnerability Database

346,508

Total vulnerabilities in the database

CVE-2026-33780 — juniper / junos

Missing Release of Memory after Effective Lifetime

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.
  • Published: Apr 9, 2026
  • Updated: Apr 10, 2026
  • CVE: CVE-2026-33780
  • Severity: Medium
  • Exploit:

CVSS v3:

  • Severity: Medium
  • Score: 6.5
  • AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWEs:

Software From Fixed in
juniper / junos - 22.4
juniper / junos 22.4 22.4.x
juniper / junos 22.4-r1 22.4-r1.x
juniper / junos 22.4-r1-s1 22.4-r1-s1.x
juniper / junos 22.4-r1-s2 22.4-r1-s2.x
juniper / junos 22.4-r2 22.4-r2.x
juniper / junos 22.4-r2-s1 22.4-r2-s1.x
juniper / junos 22.4-r2-s2 22.4-r2-s2.x
juniper / junos 22.4-r3 22.4-r3.x
juniper / junos 22.4-r3-s1 22.4-r3-s1.x
juniper / junos 22.4-r3-s2 22.4-r3-s2.x
juniper / junos 22.4-r3-s3 22.4-r3-s3.x
juniper / junos 22.4-r3-s4 22.4-r3-s4.x
juniper / junos 23.2 23.2.x
juniper / junos 23.2-r1 23.2-r1.x
juniper / junos 23.2-r1-s1 23.2-r1-s1.x
juniper / junos 23.2-r1-s2 23.2-r1-s2.x
juniper / junos 23.2-r2 23.2-r2.x
juniper / junos 23.2-r2-s1 23.2-r2-s1.x
juniper / junos 23.2-r2-s2 23.2-r2-s2.x
juniper / junos 23.4 23.4.x
juniper / junos 23.4-r1 23.4-r1.x
juniper / junos 23.4-r1-s1 23.4-r1-s1.x
juniper / junos 23.4-r1-s2 23.4-r1-s2.x
juniper / junos 23.4-r2 23.4-r2.x
juniper / junos 23.4-r2-s1 23.4-r2-s1.x
juniper / junos 23.4-r2-s2 23.4-r2-s2.x
juniper / junos 23.4-r2-s3 23.4-r2-s3.x
juniper / junos 24.2 24.2.x
juniper / junos 24.2-r1 24.2-r1.x
juniper / junos 24.2-r1-s1 24.2-r1-s1.x
juniper / junos 24.2-r1-s2 24.2-r1-s2.x
juniper / junos_os_evolved - 22.4
juniper / junos_os_evolved 22.4 22.4.x
juniper / junos_os_evolved 22.4-r1 22.4-r1.x
juniper / junos_os_evolved 22.4-r1-s1 22.4-r1-s1.x
juniper / junos_os_evolved 22.4-r1-s2 22.4-r1-s2.x
juniper / junos_os_evolved 22.4-r2 22.4-r2.x
juniper / junos_os_evolved 22.4-r2-s1 22.4-r2-s1.x
juniper / junos_os_evolved 22.4-r2-s2 22.4-r2-s2.x
juniper / junos_os_evolved 22.4-r3 22.4-r3.x
juniper / junos_os_evolved 22.4-r3-s1 22.4-r3-s1.x
juniper / junos_os_evolved 22.4-r3-s2 22.4-r3-s2.x
juniper / junos_os_evolved 22.4-r3-s3 22.4-r3-s3.x
juniper / junos_os_evolved 22.4-r3-s4 22.4-r3-s4.x
juniper / junos_os_evolved 23.2 23.2.x
juniper / junos_os_evolved 23.2-r1 23.2-r1.x
juniper / junos_os_evolved 23.2-r1-s1 23.2-r1-s1.x
juniper / junos_os_evolved 23.2-r1-s2 23.2-r1-s2.x
juniper / junos_os_evolved 23.2-r2 23.2-r2.x
juniper / junos_os_evolved 23.2-r2-s1 23.2-r2-s1.x
juniper / junos_os_evolved 23.2-r2-s2 23.2-r2-s2.x
juniper / junos_os_evolved 23.4 23.4.x
juniper / junos_os_evolved 23.4-r1 23.4-r1.x
juniper / junos_os_evolved 23.4-r1-s1 23.4-r1-s1.x
juniper / junos_os_evolved 23.4-r1-s2 23.4-r1-s2.x
juniper / junos_os_evolved 23.4-r2 23.4-r2.x
juniper / junos_os_evolved 23.4-r2-s1 23.4-r2-s1.x
juniper / junos_os_evolved 23.4-r2-s2 23.4-r2-s2.x
juniper / junos_os_evolved 23.4-r2-s3 23.4-r2-s3.x
juniper / junos_os_evolved 24.2 24.2.x
juniper / junos_os_evolved 24.2-r1 24.2-r1.x
juniper / junos_os_evolved 24.2-r1-s2 24.2-r1-s2.x

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.