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VulnerabilityPublished

CVE-2025-52949: Juniper Networks Junos OS · Improper Handling of Length Parameter Inconsistency

Affects Juniper Networks Junos OSSource CVE Database V5

0

Not known to be exploited · CVSS 6.5 Medium · fixed in 24.4R1-S3-EVO : update Juniper Networks Junos OS when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 24.4R1-S3-EVO, 24.4R1-S3, 24.2R2-S1-EVO +10
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 11 Jul 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Juniper Networks Junos OSAffected
  • 22.4 – 24.4R2-EVO
  • <21.4R3-S11
  • >=22.2 <22.2R3-S7
  • >=22.4 <22.4R3-S7
  • >=23.2 <23.2R2-S4
  • >=23.4 <23.4R2-S5
  • >=24.2 <24.2R2-S1
  • >=24.4 <24.4R1-S3
  • <22.2R3-S7-EVO
  • >=22.4-EVO <22.4R3-S7-EVO
  • >=23.2-EVO <23.2R2-S4-EVO
  • >=23.4-EVO <23.4R2-S5-EVO
  • >=24.2-EVO <24.2R2-S1-EVO
  • >=24.4-EVO <24.4R1-S3-EVO
7 affected builds
Fixed in
  • 21.4R3-S11
  • 22.2R3-S7
  • 22.4R3-S7
  • 23.2R2-S4
  • 23.4R2-S5
  • 24.2R2-S1
  • 24.4R1-S3
  • 22.2R3-S7-EVO
  • 22.4R3-S7-EVO
  • 23.2R2-S4-EVO
  • 23.4R2-S5-EVO
  • 24.2R2-S1-EVO
  • 24.4R1-S3-EVO

AI-suggested

To mitigate this vulnerability, European organizations should prioritize upgrading affected Junos OS and Junos OS Evolved devices to the fixed versions as specified by Juniper Networks. Network administrators should: 1) Identify all devices running vulnerable Junos OS versions with EVPN signaling enabled. 2) Schedule and apply vendor-released patches or upgrades to versions beyond the fixed releases (e.g., 21.4R3-S11 or later). 3) Implement strict BGP session controls, including filtering and validating BGP peers to ensure only trusted and authenticated peers can establish sessions, reducing the risk of malicious adjacent peers. 4) Monitor BGP session stability and rpd process health to detect anomalous crashes or restarts promptly. 5) Employ network segmentation to limit the exposure of BGP peers and EVPN signaling to only necessary network segments, minimizing the attack surface. 6) Use logging and alerting mechanisms to detect malformed BGP packets or unusual traffic patterns indicative of exploitation attempts. 7) Consider deploying redundancy and failover mechanisms to maintain network availability during potential DoS events. These measures, combined with timely patching, will reduce the likelihood and impact of exploitation.

Description

An Improper Handling of Length Parameter Inconsistency vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a logically adjacent BGP peer sending a specifically malformed BGP packet to cause rpd to crash and restart, resulting in a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. Only systems configured for Ethernet Virtual Private Networking (EVPN) signaling are vulnerable to this issue. This issue affects iBGP and eBGP, and both IPv4 and IPv6 are affected by this vulnerability.This issue affects: Junos OS:  * all versions before 21.4R3-S11,  * from 22.2 before 22.2R3-S7,  * from 22.4 before 22.4R3-S7,  * from 23.2 before 23.2R2-S4,  * from 23.4 before 23.4R2-S5,  * from 24.2 before 24.2R2-S1,  * from 24.4 before 24.4R1-S3, 24.4R2;  Junos OS Evolved:  * all versions before 22.2R3-S7-EVO,  * from 22.4-EVO before 22.4R3-S7-EVO,  * from 23.2-EVO before 23.2R2-S4-EVO,  * from 23.4-EVO before 23.4R2-S5-EVO,  * from 24.2-EVO before 24.2R2-S1-EVO,  * from 24.4-EVO before 24.4R1-S3-EVO, 24.4R2-EVO.

References

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