CVE-2024-21606Network attack vector

Unauthenticated flowd crash via double free

Published Jan 12, 2024 · Updated Jun 17, 2025

Double free in flowd in Juniper Networks Junos OS on SRX Series allows remote attackers to crash flowd via a crafted packet sequence. flowd releases the same allocation twice, but Juniper has not disclosed the affected object or the packet-processing path that triggers the second free. Reachability requires a remote access VPN with a tcp-encap-profile; successful exploitation interrupts traffic while flowd restarts.

CVSS severity7.5
High
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Double free in flowd in Juniper Networks Junos OS on SRX Series allows remote attackers to crash flowd via a crafted packet sequence. flowd releases the same allocation twice, but Juniper has not disclosed the affected object or the packet-processing path that triggers the second free. Reachability requires a remote access VPN with a tcp-encap-profile; successful exploitation interrupts traffic while flowd restarts.

The record

CVE
CVE-2024-21606
Published
Jan 12, 2024
Updated
Jun 17, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-415, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 17, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <20.4R3-S8
  2. Affected versionversion=21.2 <21.2R3-S6
  3. Affected versionversion=21.3 <21.3R3-S5
  4. Affected versionversion=21.4 <21.4R3-S5
  5. Affected versionversion=22.1 <22.1R3-S3
  6. Affected versionversion=22.2 <22.2R3-S3
  7. Affected versionversion=22.3 <22.3R3-S1
  8. Affected versionversion=22.4 <22.4R2-S2, 22.4R3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <20.4R3-S8; version=21.2 <21.2R3-S6; version=21.3 <21.3R3-S5; version=21.4 <21.4R3-S5; version=22.1 <22.1R3-S3; version=22.2 <22.2R3-S3; version=22.3 <22.3R3-S1; version=22.4 <22.4R2-S2, 22.4R3

Published CVSS scores

7.5Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo