CVE-2026-33780 Junos OS and Junos OS Evolved: In an EVPN-MPLS scenario churn of ESI routes causes a memory leak in l2ald
An adjacent attacker can cause a memory leak in the l2ald process via ESI route churn, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-33780?
CVE-2026-33780 is a high-severity denial of service vulnerability in Juniper Junos, published on 9 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-401
Which versions are affected by CVE-2026-33780?
It affects 2 products.
Products include Juniper Junos, Juniper Junos Os Evolved.
How do I fix CVE-2026-33780?
No fix has been published for CVE-2026-33780 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-33780 being exploited?
There is no known exploitation of CVE-2026-33780 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos
- CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification
- CVE-2020-1631 Juniper Junos OS Path Traversal
- CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization
- CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function
- CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification
Sources
Also known as GHSA-wcmx-9w9j-q7ph.