CVE-2021-0239 json
Junos OS Evolved: Denial of Service due to receipt of specific genuine layer 2 frames.
published 2021-04-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-2858
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 32%
- public exploits
- 0
- none known
Summary
In Juniper Networks Junos OS Evolved, receipt of a stream of specific genuine Layer 2 frames may cause the Advanced Forwarding Toolkit (AFT) manager process (Evo-aftmand), responsible for handling Route, Class-of-Service (CoS), Firewall operations within the packet forwarding engine (PFE) to crash and restart, leading to a Denial of Service (DoS) condition. By continuously sending this specific stream of genuine Layer 2 frames, an attacker can repeatedly crash the PFE, causing a sustained Denial of Service (DoS). This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R1-EVO. This issue does not affect Junos OS versions.
Patch / fix
- Juniper Networks Junos OS Evolved 20.4R1-EVO
Exploit prediction
0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVD | 3.1 | 6.5 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVD | 2.0 | 6.1 | AV:A/AC:L/Au:N/C:N/I:N/A:C |
Affected products
- Juniper Networks Junos OS Evolved
Classification
- Weakness
-
- CWE-754 Improper Check for Unusual or Exceptional Conditions
References
-
kb.juniper.net
/JSA11134
vendor-advisory
Sources
- CVE List CVE-2021-0239
- NVD CVE-2021-0239
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