CVE-2026-33778Network attack vector

VPN connection denial via malformed ISAKMP packet

Published Apr 9, 2026 · Updated Apr 9, 2026

Input validation failure in Juniper Networks Junos OS allows remote attackers to crash kmd or iked with a malformed ISAKMP packet. The IPsec library used by kmd and iked accepts a syntactically malformed first initiator packet instead of rejecting it, causing the process to restart. No authentication or user interaction is required; one packet briefly blocks new security associations, while repeated packets prevent new VPN connections.

CVSS severity8.7
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Input validation failure in Juniper Networks Junos OS allows remote attackers to crash kmd or iked with a malformed ISAKMP packet. The IPsec library used by kmd and iked accepts a syntactically malformed first initiator packet instead of rejecting it, causing the process to restart. No authentication or user interaction is required; one packet briefly blocks new security associations, while repeated packets prevent new VPN connections.

The record

CVE
CVE-2026-33778
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-1286, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=0 <22.4R3-S9
  2. Affected versionversion=23.2 <23.2R2-S6
  3. Affected versionversion=23.4 <23.4R2-S7
  4. Affected versionversion=24.2 <24.2R2-S4
  5. Affected versionversion=24.4 <24.4R2-S3
  6. Affected versionversion=25.2 <25.2R1-S2, 25.2R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <22.4R3-S9; version=23.2 <23.2R2-S6; version=23.4 <23.4R2-S7; version=24.2 <24.2R2-S4; version=24.4 <24.4R2-S3; version=25.2 <25.2R1-S2, 25.2R2

Published CVSS scores

7.5Juniper NetworksCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7Juniper NetworksCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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.

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Technologies

Your stack

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Your stack

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