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VulnerabilityPublished

CVE-2026-33781: Juniper Networks Junos OS · Unchecked Error Condition

Affects Juniper Networks Junos OSSource CVE Database V5

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Not known to be exploited · CVSS 6.5 Medium : upgrade to 25.2R1-S1 or 24.4R2 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 25.2R1-S1, 24.4R2
CVSS:3.1/AV:A/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 30 Oct 2026.

What to do

Upgrade Juniper Networks Junos OS to 25.2R1-S1 or 24.4R2.

Affected software

ProductAffectedFixed in
Juniper NetworksJunos OSAffected
  • >=24.4 <24.4R2
  • =25.2
Fixed in
  • 25.2R1-S1
  • 24.4R2

AI-suggested

If you cannot patch yet, network operators should consider disabling the affected features (L2PT on UNI or VSTP on NNI in VXLAN scenarios) if feasible or implement network controls to prevent receipt of VSTP BPDUs on UNI interfaces from untrusted adjacent sources. Manual device restart is required to recover from the denial of service condition.

Description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX and QFX Series devices allow an unauthenticated, adjacent attacker to cause a complete Denial of Service (DoS). On EX4k, and QFX5k platforms configured as service-provider edge devices, if L2PT is enabled on the UNI and VSTP is enabled on NNI in VXLAN scenarios, receiving VSTP BPDUs on UNI leads to packet buffer allocation failures, resulting in the device to not pass traffic anymore until it is manually recovered with a restart.This issue affects Junos OS: * 24.4 releases before 24.4R2, * 25.2 releases before 25.2R1-S1, 25.2R2. This issue does not affect Junos OS releases before 24.4R1.

References

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