Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-33797

Severity CVSS v4.0:
HIGH
Type:
CWE-20 Input Validation
Publication date:
09/04/2026
Last modified:
23/04/2026

Description

An Improper Input Validation vulnerability in Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, adjacent attacker, sending a specific genuine BGP packet in an already established BGP session to reset only that session causing a Denial of Service (DoS).<br /> <br /> An attacker repeatedly sending the packet will sustain the Denial of Service (DoS).This issue affects Junos OS:<br /> <br /> * 25.2 versions before 25.2R2<br /> <br /> <br /> This issue does not affect Junos OS versions before 25.2R1.<br /> <br /> This issue affects Junos OS Evolved: <br /> * 25.2-EVO versions before 25.2R2-EVO<br /> <br /> <br /> This issue does not affect Junos OS Evolved versions before 25.2R1-EVO.<br /> <br /> eBGP and iBGP are affected.<br /> IPv4 and IPv6 are affected.

Impact

Vector 4.0
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/AU:Y/R:A/V:C/RE:M/U:Green CVSS v4.0 Severity and Metrics:

Base Score: 7.10 HIGH
Vector: 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/AU:Y/R:A/V:C/RE:M/U:Green

Attack Vector (AV): Adjacent
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): None
Availability (VA): High
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): Low
Automatable (AU): Yes
Recovery (R): Automatic
Value Density (V): Concentrated
Vulnerability Response Effort (RE): Moderate
Provider Urgency (U): Green

Base Score 4.0
7.10
Severity 4.0
HIGH
Vector 3.x
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.40 HIGH
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector (AV): Adjacent
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Changed
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x
7.40
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
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:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:25.2:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:25.2:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:25.2:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:25.2:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:25.2:r1-s2:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools