CVE-2026-33797

BGP session reset via improper packet validation

Published Apr 9, 2026 · Updated Apr 9, 2026

Improper BGP validation in Juniper Networks Junos OS 25.2 before 25.2R2 and Junos OS Evolved 25.2 before 25.2R2-EVO allows session resets. The BGP process mishandles a specific genuine IPv4 or IPv6 BGP packet received in an established eBGP or iBGP session and resets only that session. Reachability requires adjacency to an established BGP peer session; repeated delivery sustains the routing-session interruption without crashing the device.

CVSS severity7.1
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper BGP validation in Juniper Networks Junos OS 25.2 before 25.2R2 and Junos OS Evolved 25.2 before 25.2R2-EVO allows session resets. The BGP process mishandles a specific genuine IPv4 or IPv6 BGP packet received in an established eBGP or iBGP session and resets only that session. Reachability requires adjacency to an established BGP peer session; repeated delivery sustains the routing-session interruption without crashing the device.

The record

CVE
CVE-2026-33797
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-20, T1499.004
Attack vector
adjacent
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=25.2 <25.2R2-EVO

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=25.2 <25.2R2-EVO
Juniper Networks · Junos OSversion=25.2 <25.2R2

Published CVSS scores

7.1Juniper Networks, Inc.CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L
7.4Juniper Networks, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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