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.
- Published
- Updated
- Reserved
- Assigned by
- juniper
Description
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| juniperCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 1.3% · top 29% of all CVEs (6 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
- CWE-696 Incorrect Behavior Order (opens in a new tab)All about CWE-696 and its CVEs
- Denial of Service (DoS)
Affected products
- unaffected unspecified – < 17.2R1
- affected 17.2R1 – < 17.2*
- affected 17.3 – < 17.3R3-S9
- affected 17.4 – < 17.4R2-S12, 17.4R3-S3
- affected 18.1 – < 18.1R3-S11
- affected 18.2 – < 18.2R2-S6, 18.2R3-S3
- affected 18.3 – < 18.3R2-S4, 18.3R3-S1
- affected 18.4 – < 18.4R1-S8, 18.4R2-S5, 18.4R3
- affected 19.1 – < 19.1R1-S6, 19.1R2-S2, 19.1R3
- affected 19.2 – < 19.2R1-S5, 19.2R2
- affected 19.3 – < 19.3R2-S5, 19.3R3
What to do
Solution: The following software releases have been updated to resolve this specific issue: 17.3R3-S9, 17.4R2-S12, 17.4R3-S3, 18.1R3-S11, 18.2R2-S6, 18.2R3-S3, 18.3R2-S4, 18.3R3-S1, 18.4R1-S8, 18.4R2-S5, 18.4R3, 19.1R1-S6, 19.1R2-S2, 19.1R3, 19.2R1-S5, 19.2R2, 19.3R2-S5, 19.3R3, 19.4R1, and all subsequent releases.
Workaround: To work around this issue customers can either: 1. Disable Mapping of Address and port - Encapsulation (MAP-E) as an inline service on MX Series routers that use MPC and MIC interfaces. or 2. Determine where the MAP-E v4 or v6 reassembly exists, review the following hierarchies and disable the "v4-reassembly;" and "v6-reassembly;" options where they exist: [services softwire softwire-concentrator] [services softwires softwire-types] [security softwires] and the following syntaxes: map-e name { v4-reassembly; <<<<< DISABLE the v4-reassembly option. v6-reassembly; <<<<< DISABLE the v6-reassembly option. }
Exploitation: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
References (2)
- https://kb.juniper.net/JSA11247 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://www.juniper.net/documentation/en_US/junos/topics/topic-map/map-e-configuring.html (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-31379)Record last updated .