# CVE-2026-21918

## Summary

- **CVE ID:** CVE-2026-21918
- **Severity:** HIGH
- **CVSS Score:** 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M)
- **CWE:** CWE-415
- **Published:** Jan 15, 2026
- **Last Modified:** Mar 12, 2026

## Description

A Double Free vulnerability in the flow processing daemon (flowd) of Juniper Networks Junos OS on SRX and MX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). On all SRX and MX Series platforms, when during TCP session establishment a specific sequence of packets is encountered a double free happens. This causes flowd to crash and the respective FPC to restart.





This issue affects Junos OS on SRX and MX Series:



  *  all versions before 22.4R3-S7,
  *  23.2 versions before 23.2R2-S3,
  *  23.4 versions before 23.4R2-S4,
  *  24.2 versions before 24.2R2.

## Affected Products

- Juniper Networks — Junos OS (0)
- Juniper Networks — Junos OS (23.2)
- Juniper Networks — Junos OS (23.4)
- Juniper Networks — Junos OS (24.2)

## References

- [CNA](https://supportportal.juniper.net/JSA106018)
- [CNA](https://kb.juniper.net/JSA106018)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.39%
- **EPSS Percentile:** 32.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._