CVE-2023-36841
Junos OS: MX Series: Receipt of malformed TCP traffic will cause a Denial of Service
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS).
An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover.
This issue affects interfaces with PPPoE configured and tcp-mss enabled.
This issue affects Juniper Networks Junos OS
- All versions prior to 20.4R3-S7;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S6;
- 21.3 versions prior to 21.3R3-S5;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S4;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Junos OS: MX Series: Receipt of malformed TCP traffic will cause a Denial of Service
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS).
An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover.
This issue affects interfaces with PPPoE configured and tcp-mss enabled.
This issue affects Juniper Networks Junos OS
- All versions prior to 20.4R3-S7;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S6;
- 21.3 versions prior to 21.3R3-S5;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S4;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
- Record
CVE-2023-36841- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
EUVDEUVD-2023-40761
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS).
An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover.
This issue affects interfaces with PPPoE configured and tcp-mss enabled.
This issue affects Juniper Networks Junos OS
- All versions prior to 20.4R3-S7;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S6;
- 21.3 versions prior to 21.3R3-S5;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S4;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
- Record
EUVD-2023-40761- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-j5xw-gh42-g53c
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding...
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS).
An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover.
This issue affects interfaces with PPPoE configured and tcp-mss enabled.
This issue affects Juniper Networks Junos OS
- All versions prior to 20.4R3-S7;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S6;
- 21.3 versions prior to 21.3R3-S5;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S4;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
- Record
GHSA-j5xw-gh42-g53c- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
NVD
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS).
An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover.
This issue affects interfaces with PPPoE configured and tcp-mss enabled.
This issue affects Juniper Networks Junos OS
- All versions prior to 20.4R3-S7;
- 21.1 version 21.1R1 and later versions;
- 21.2 versions prior to 21.2R3-S6;
- 21.3 versions prior to 21.3R3-S5;
- 21.4 versions prior to 21.4R3-S3;
- 22.1 versions prior to 22.1R3-S4;
- 22.2 versions prior to 22.2R3;
- 22.3 versions prior to 22.3R2-S2;
- 22.4 versions prior to 22.4R2;
- Record
CVE-2023-36841- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-36841 is a high vulnerability (CVSS 7.5) in Juniper Junos, published October 12, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.62%, the 49th percentile. No source names a fixed version.