CVE-2024-21616Network attack vector

Network traffic interruption via SIP NAT exhaustion

Published Jan 12, 2024 · Updated Jun 17, 2025

Improper input validation in Junos OS on MX and SRX Series allows remote attackers to interrupt NAT traffic with a crafted SIP packet. With SIP ALG enabled, the PFE accepts a specific malformed SIP message and consumes NAT IP allocations needed by legitimate connections. Repeated packets sustain the allocation failure, preventing genuine NAT traffic until the condition clears.

CVSS severity7.5
High
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Junos OS on MX and SRX Series allows remote attackers to interrupt NAT traffic with a crafted SIP packet. With SIP ALG enabled, the PFE accepts a specific malformed SIP message and consumes NAT IP allocations needed by legitimate connections. Repeated packets sustain the allocation failure, preventing genuine NAT traffic until the condition clears.

The record

CVE
CVE-2024-21616
Published
Jan 12, 2024
Updated
Jun 17, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-1286, 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 <21.2R3-S6
  2. Affected versionversion=21.3 <21.3R3-S5
  3. Affected versionversion=21.4 <21.4R3-S5
  4. Affected versionversion=22.1 <22.1R3-S4
  5. Affected versionversion=22.2 <22.2R3-S3
  6. Affected versionversion=22.3 <22.3R3-S1
  7. Affected versionversion=22.4 <22.4R2-S2, 22.4R3
  8. Affected versionversion=23.2 <23.2R1-S1, 23.2R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <21.2R3-S6; version=21.3 <21.3R3-S5; version=21.4 <21.4R3-S5; version=22.1 <22.1R3-S4; version=22.2 <22.2R3-S3; version=22.3 <22.3R3-S1; version=22.4 <22.4R2-S2, 22.4R3; version=23.2 <23.2R1-S1, 23.2R2

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-1286Improper Validation of Syntactic Correctness of Input
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

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Your stack

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