CVE-2021-31379
Junos OS: MX Series: MPC 7/8/9/10/11 cards with MAP-E: PFE halts when an attacker sends malformed IPv4 or IPv6 traffic inside the MAP-E tunnel.
An Incorrect Behavior Order vulnerability in the MAP-E automatic tunneling mechanism of Juniper Networks Junos OS allows an attacker to send certain malformed IPv4 or IPv6 packets to cause a Denial of Service (DoS) to the PFE on the device which is disabled as a result of the processing of these packets. Continued receipt and processing of these malformed IPv4 or IPv6 packets will create a sustained Denial of Service (DoS) condition. This issue only affects MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. An indicator of compromise is the output: FPC ["FPC ID" # e.g. "0"] PFE #{PFE ID # e.g. "1"] : Fabric Disabled Example: FPC 0 PFE #1 : Fabric Disabled when using the command: show chassis fabric fpcs An example of a healthy result of the command use would be: user@device-re1> show chassis fabric fpcs Fabric management FPC state: FPC 0 PFE #0 Plane 0: Plane enabled Plane 1: Plane enabled Plane 2: Plane enabled Plane 3: Plane enabled Plane 4: Plane enabled Plane 5: Plane enabled Plane 6: Plane enabled Plane 7: Plane enabled This issue affects: Juniper Networks Junos OS on MX Series with MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. 17.2 version 17.2R1 and later versions; 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R2-S6, 18.2R3-S3; 18.3 versions prior to 18.3R2-S4, 18.3R3-S1; 18.4 versions prior to 18.4R1-S8, 18.4R2-S5, 18.4R3; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S5, 19.3R3. This issue does not affect Juniper Networks Junos OS versions prior to 17.2R1.
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: MPC 7/8/9/10/11 cards with MAP-E: PFE halts when an attacker sends malformed IPv4 or IPv6 traffic inside the MAP-E tunnel.
An Incorrect Behavior Order vulnerability in the MAP-E automatic tunneling mechanism of Juniper Networks Junos OS allows an attacker to send certain malformed IPv4 or IPv6 packets to cause a Denial of Service (DoS) to the PFE on the device which is disabled as a result of the processing of these packets. Continued receipt and processing of these malformed IPv4 or IPv6 packets will create a sustained Denial of Service (DoS) condition. This issue only affects MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. An indicator of compromise is the output: FPC ["FPC ID" # e.g. "0"] PFE #{PFE ID # e.g. "1"] : Fabric Disabled Example: FPC 0 PFE #1 : Fabric Disabled when using the command: show chassis fabric fpcs An example of a healthy result of the command use would be: user@device-re1> show chassis fabric fpcs Fabric management FPC state: FPC 0 PFE #0 Plane 0: Plane enabled Plane 1: Plane enabled Plane 2: Plane enabled Plane 3: Plane enabled Plane 4: Plane enabled Plane 5: Plane enabled Plane 6: Plane enabled Plane 7: Plane enabled This issue affects: Juniper Networks Junos OS on MX Series with MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. 17.2 version 17.2R1 and later versions; 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R2-S6, 18.2R3-S3; 18.3 versions prior to 18.3R2-S4, 18.3R3-S1; 18.4 versions prior to 18.4R1-S8, 18.4R2-S5, 18.4R3; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S5, 19.3R3. This issue does not affect Juniper Networks Junos OS versions prior to 17.2R1.
- Record
CVE-2021-31379- 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-696
- Updated
- 2026-11-02
EUVDEUVD-2021-18289
An Incorrect Behavior Order vulnerability in the MAP-E automatic tunneling mechanism of Juniper Networks Junos OS allows an attacker to send certain malformed IPv4 or IPv6 packets to cause a Denial of Service (DoS) to the PFE on the device which is disabled as a result of the processing of these packets. Continued receipt and processing of these malformed IPv4 or IPv6 packets will create a sustained Denial of Service (DoS) condition. This issue only affects MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. An indicator of compromise is the output: FPC ["FPC ID" # e.g. "0"] PFE #{PFE ID # e.g. "1"] : Fabric Disabled Example: FPC 0 PFE #1 : Fabric Disabled when using the command: show chassis fabric fpcs An example of a healthy result of the command use would be: user@device-re1> show chassis fabric fpcs Fabric management FPC state: FPC 0 PFE #0 Plane 0: Plane enabled Plane 1: Plane enabled Plane 2: Plane enabled Plane 3: Plane enabled Plane 4: Plane enabled Plane 5: Plane enabled Plane 6: Plane enabled Plane 7: Plane enabled This issue affects: Juniper Networks Junos OS on MX Series with MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. 17.2 version 17.2R1 and later versions; 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R2-S6, 18.2R3-S3; 18.3 versions prior to 18.3R2-S4, 18.3R3-S1; 18.4 versions prior to 18.4R1-S8, 18.4R2-S5, 18.4R3; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S5, 19.3R3. This issue does not affect Juniper Networks Junos OS versions prior to 17.2R1.
- Record
EUVD-2021-18289- 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-g3mf-xh9x-gcpp No score
An Incorrect Behavior Order vulnerability in the MAP-E automatic tunneling mechanism of Juniper...
An Incorrect Behavior Order vulnerability in the MAP-E automatic tunneling mechanism of Juniper Networks Junos OS allows an attacker to send certain malformed IPv4 or IPv6 packets to cause a Denial of Service (DoS) to the PFE on the device which is disabled as a result of the processing of these packets. Continued receipt and processing of these malformed IPv4 or IPv6 packets will create a sustained Denial of Service (DoS) condition. This issue only affects MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. An indicator of compromise is the output: FPC ["FPC ID" # e.g. "0"] PFE #{PFE ID # e.g. "1"] : Fabric Disabled Example: FPC 0 PFE #1 : Fabric Disabled when using the command: show chassis fabric fpcs An example of a healthy result of the command use would be: user@device-re1> show chassis fabric fpcs Fabric management FPC state: FPC 0 PFE #0 Plane 0: Plane enabled Plane 1: Plane enabled Plane 2: Plane enabled Plane 3: Plane enabled Plane 4: Plane enabled Plane 5: Plane enabled Plane 6: Plane enabled Plane 7: Plane enabled This issue affects: Juniper Networks Junos OS on MX Series with MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. 17.2 version 17.2R1 and later versions; 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R2-S6, 18.2R3-S3; 18.3 versions prior to 18.3R2-S4, 18.3R3-S1; 18.4 versions prior to 18.4R1-S8, 18.4R2-S5, 18.4R3; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S5, 19.3R3. This issue does not affect Juniper Networks Junos OS versions prior to 17.2R1.
- Record
GHSA-g3mf-xh9x-gcpp- Updated
- 2026-11-02
NVD
An Incorrect Behavior Order vulnerability in the MAP-E automatic tunneling mechanism of Juniper Networks Junos OS allows an attacker to send certain malformed IPv4 or IPv6 packets to cause a Denial of Service (DoS) to the PFE on the device which is disabled as a result of the processing of these packets. Continued receipt and processing of these malformed IPv4 or IPv6 packets will create a sustained Denial of Service (DoS) condition. This issue only affects MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. An indicator of compromise is the output: FPC ["FPC ID" # e.g. "0"] PFE #{PFE ID # e.g. "1"] : Fabric Disabled Example: FPC 0 PFE #1 : Fabric Disabled when using the command: show chassis fabric fpcs An example of a healthy result of the command use would be: user@device-re1> show chassis fabric fpcs Fabric management FPC state: FPC 0 PFE #0 Plane 0: Plane enabled Plane 1: Plane enabled Plane 2: Plane enabled Plane 3: Plane enabled Plane 4: Plane enabled Plane 5: Plane enabled Plane 6: Plane enabled Plane 7: Plane enabled This issue affects: Juniper Networks Junos OS on MX Series with MPC 7/8/9/10/11 cards, when MAP-E IP reassembly is enabled on these cards. 17.2 version 17.2R1 and later versions; 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R2-S6, 18.2R3-S3; 18.3 versions prior to 18.3R2-S4, 18.3R3-S1; 18.4 versions prior to 18.4R1-S8, 18.4R2-S5, 18.4R3; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S5, 19.3R3. This issue does not affect Juniper Networks Junos OS versions prior to 17.2R1.
- Record
CVE-2021-31379- 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 - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:N/I:N/A:P - Weakness
- CWE-696
- 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-2021-31379 is a high vulnerability (CVSS 7.5) in Juniper Junos, published October 19, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.34%, the 71st percentile. No source names a fixed version.