CVE-2021-0207
What it is
An improper interpretation conflict of certain data between certain software components within the Juniper Networks Junos OS devices does not allow certain traffic to pass through the device upon receipt from an ingress interface filtering certain specific types of traffic which is then being redirected to an egress interface on a different VLAN. This causes a Denial of Service (DoS) to those clients sending these particular types of traffic. Such traffic being sent by a client may appear genuine, but is non-standard in nature and should be considered as potentially malicious, and can be targeted to the device, or destined through it for the issue to occur. This issues affects IPv4 and IPv6 traffic. An indicator of compromise may be found by checking log files. You may find that traffic on the input interface has 100% of traffic flowing into the device, yet the egress interface shows 0 pps leaving the device. For example: [show interfaces "interface" statistics detail] Output between two interfaces would reveal something similar to: Ingress, first interface: -------------------- Interface Link Input packets (pps) Output packets (pps) et-0/0/0 Up 9999999999 (9999) 1 (0) -------------------- Egress, second interface: -------------------- Interface Link Input packets (pps) Output packets (pps) et-0/0/1 Up 0 (0) 9999999999 (0) -------------------- Dropped packets will not show up in DDoS monitoring/protection counters as issue is not caused by anti-DDoS protection mechanisms. This issue affects: Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S7 on NFX250, QFX5K Series, EX4600; 17.4 versions prior to 17.4R2-S11, 17.4R3-S3 on NFX250, QFX5K Series, EX4600; 18.1 versions prior to 18.1R3-S9 on NFX250, QFX5K Series, EX2300 Series, EX3400 Series, EX4600; 18.2 versions prior to 18.2R3-S3 on NFX250, QFX5K Series, EX2300 Series, EX3400 Series, EX4300 Multigigabit, EX4600; 18.3 versions prior to 18.3R3-S1 on NFX250, QFX5K Series, EX2300 Series, EX3400 Series, EX4300 Multigigabit, EX4600 Series; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3 on NFX250, QFX5K Series, EX2300 Series, EX3400 Series, EX4300 Multigigabit, EX4600 Series; 19.1 versions prior to 19.1R1-S5, 19.1R2-S1, 19.1R3 on NFX250, QFX5K Series, EX2300 Series, EX3400 Series, EX4300 Multigigabit, EX4600 Series; 19.2 versions prior to 19.2R1-S5, 19.2R2 on NFX250, QFX5K Series, EX2300 Series, EX3400 Series, EX4300 Multigigabit, EX4600 Series; 19.3 versions prior to 19.3R2-S3, 19.3R3 on NFX250, QFX5K Series, EX2300 Series, EX3400 Series, EX4300 Multigigabit, EX4600 Series; 19.4 versions prior to 19.4R1-S2, 19.4R2 on NFX250, NFX350, QFX5K Series, EX2300 Series, EX3400 Series, EX4300 Multigigabit, EX4600 Series. This issue does not affect Junos OS releases prior to 17.2R2.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 1.3% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 1.3% in the next 30 days (EPSS).
- Severity: 7.5 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 1.3% · EPSS, next 30 days
- Weakness
- CWE-115
- Record status
- Modified
Affected
- Juniper Junos 17.3
- Juniper Junos 17.4
- Juniper Junos 18.1
- Juniper Junos 18.2
- Juniper Junos 18.3
- Juniper Junos 18.4
- Juniper Junos 19.1
- Juniper Junos 19.2
Attack profile CVSS 3.1 · 7.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-0207.md and follow it. Check whether this project is affected by CVE-2021-0207. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
