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VulnerabilityPublished

CVE-2026-33778: Juniper Networks Junos OS · Improper Validation of Syntactic Correctness of Input

Affects Juniper Networks Junos OSSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 25.2R1-S2 : patch Juniper Networks Junos OS soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 25.2R1-S2, 24.4R2-S3, 24.2R2-S4 +3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Juniper NetworksJunos OSAffected
  • <22.4R3-S9
  • >=23.2 <23.2R2-S6
  • >=23.4 <23.4R2-S7
  • >=24.2 <24.2R2-S4
  • >=24.4 <24.4R2-S3
  • =25.2
Fixed in
  • 25.2R1-S2
  • 24.4R2-S3
  • 24.2R2-S4
  • 23.4R2-S7
  • 23.2R2-S6
  • 22.4R3-S9

AI-suggested

A patch is available for this vulnerability. Since the affected Junos OS is a cloud-hosted service, Juniper Networks manages remediation server-side. Users should ensure their devices are updated to the fixed versions listed (22.4R3-S9 or later, 23.2R2-S6 or later, 23.4R2-S7 or later, 24.2R2-S4 or later, 24.4R2-S3 or later, 25.2R1-S2 or later). Check the vendor advisory for the latest patch and update guidance.

Description

An Improper Validation of Syntactic Correctness of Input vulnerability in the IPsec library used by kmd and iked of Juniper Networks Junos OS on SRX Series and MX Series allows an unauthenticated, network-based attacker to cause a complete Denial-of-Service (DoS). If an affected device receives a specifically malformed first ISAKMP packet from the initiator, the kmd/iked process will crash and restart, which momentarily prevents new security associations (SAs) for from being established. Repeated exploitation of this vulnerability causes a complete inability to establish new VPN connections. This issue affects Junos OS on SRX Series and MX Series: * all versions before 22.4R3-S9, * 23.2 version before 23.2R2-S6, * 23.4 version before 23.4R2-S7, * 24.2 versions before 24.2R2-S4, * 24.4 versions before 24.4R2-S3, * 25.2 versions before 25.2R1-S2, 25.2R2.

References

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