CVE-2026-33781: An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of

Routine

MEDIUM 6.5MITIGATE

CVE-2026-33781 is a medium-severity flaw (CVSS 6.5) affecting junos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 94%)
CISA exploited list	No
Weakness	CWE-754
Published	2026-04-09
Last modified	2026-10-26

Publisher (CNA): Juniper Networks, Inc. · Vendor: juniper

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-09 22:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

juniper junos MITIGATE

Affected: 24.4 · 24.4 r1 · 24.4 r1-s2 · 24.4 r1-s3 · 25.2 · 25.2 r1 · 25.2 r2

Fixed in: no fixed release known

Safe to downgrade to: a release before 24.4

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-33781?

junos: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-33781 being exploited?

CVE-2026-33781 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-33781 affect?

CVE-2026-33781 affects junos. Severity is medium (CVSS 6.5). 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 D

How urgent is CVE-2026-33781?

Priority 24/100. No elevated risk signals yet.

Software pages

Juniper Junos vulnerabilities

Related CVEs

CVE-2026-33790 HIGH 7.5 UPGRADE An Improper Check for Unusual or Exceptional Conditions vulnerability in the flow daemon (flowd) of Juniper Ne
CVE-2026-33791 MEDIUM 6.7 UPGRADE UPGRADE An OS Command Injection vulnerability in the CLI processing of Juniper Networks Junos OS and Junos OS Evolved
CVE-2026-33785 HIGH 8.8 MITIGATE A Missing Authorization vulnerability in the CLI of Juniper Networks Junos OS on MX Series allows a local, aut
CVE-2026-33793 HIGH 7.8 UPGRADE UPGRADE An Execution with Unnecessary Privileges vulnerability in the User Interface (UI) of Juniper Networks Junos OS
CVE-2026-33773 MEDIUM 5.8 MITIGATE An Incorrect Initialization of Resource vulnerability in the packet forwarding engine (pfe) of Juniper Network

References

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