How severe is CVE-2026-33781?

CVE-2026-33781 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-33781 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33781?

CVE-2026-33781 primarily affects Juniper Junos. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-33781?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-33781 have an EU (EUVD) identifier?

Yes. CVE-2026-33781 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21199.

When was CVE-2026-33781 published?

CVE-2026-33781 was published on 2026-04-09 and last updated on 2026-06-17.

CVE-2026-33781

CVE-2026-33781 is a medium-severity vulnerability in Juniper Junos with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-754.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 7.1
EPSS exploit prediction: 0% (6th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-21199
Weakness: CWE-754
Affected product: Juniper Junos
Published: 2026-04-09
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-33781?: 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.
How severe is CVE-2026-33781?: CVE-2026-33781 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-33781 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33781?: CVE-2026-33781 primarily affects Juniper Junos. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-33781?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-33781 have an EU (EUVD) identifier?: Yes. CVE-2026-33781 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21199.
When was CVE-2026-33781 published?: CVE-2026-33781 was published on 2026-04-09 and last updated on 2026-06-17.

References

https://kb.juniper.net/JSA107869

Affected products (7)

cpe:2.3:o:juniper:junos:24.4:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.4:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.4:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.4:r1-s3:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:25.2:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:25.2:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:25.2:r2:*:*:*:*:*:*

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