CVE-2024-21607Network attack vector

IPv6 filter bypass via unsupported payload matching

Published Jan 12, 2024 · Updated Jun 17, 2025

Firewall filter bypass in Junos OS on MX Series and EX9200 Series allows remote attackers to pass IPv6 packets meant to be rejected. The kernel filter does not support payload-protocol matching, so a reject action with tcp-reset accepts every matching packet without further action. Exploitation requires an IPv6 filter using both options; IPv4 filters are unaffected, and the bypass permits traffic without changing device configuration.

CVSS severity5.3
Medium
EPSS probability0.31%
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

Firewall filter bypass in Junos OS on MX Series and EX9200 Series allows remote attackers to pass IPv6 packets meant to be rejected. The kernel filter does not support payload-protocol matching, so a reject action with tcp-reset accepts every matching packet without further action. Exploitation requires an IPv6 filter using both options; IPv4 filters are unaffected, and the bypass permits traffic without changing device configuration.

The record

CVE
CVE-2024-21607
Published
Jan 12, 2024
Updated
Jun 17, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-447, T1190
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-S7
  2. Affected versionversion=21.1 <21.1R3-S5
  3. Affected versionversion=21.2 <21.2R3-S5
  4. Affected versionversion=21.3 <21.3R3-S4
  5. Affected versionversion=21.4 <21.4R3-S4
  6. Affected versionversion=22.1 <22.1R3-S2
  7. Affected versionversion=22.2 <22.2R3-S2
  8. Affected versionversion=22.3 <22.3R2-S2, 22.3R3
  9. Affected versionversion=22.4 <22.4R1-S2, 22.4R2-S2, 22.4R3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <20.4R3-S7; version=21.1 <21.1R3-S5; version=21.2 <21.2R3-S5; version=21.3 <21.3R3-S4; version=21.4 <21.4R3-S4; version=22.1 <22.1R3-S2; version=22.2 <22.2R3-S2; version=22.3 <22.3R2-S2, 22.3R3; version=22.4 <22.4R1-S2, 22.4R2-S2, 22.4R3

Published CVSS scores

5.3Juniper NetworksCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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-447Unimplemented or Unsupported Feature in UI
T1190Exploit Public-Facing Application

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