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2020-07 Security Bulletin: Junos OS: MX Series: PFE crash on MPC7/8/9 upon receipt of large packets requiring fragmentation (CVE-2020-1655)



Article ID: JSA11041 SECURITY_ADVISORIES Last Updated: 28 Jul 2020Version: 2.0
Product Affected:
This issue affects Junos OS 17.2, 17.3, 17.4, 18.1, 18.2, 18.2X75, 18.3, 18.4, 19.1, 19.2, 19.3. Affected platforms: MX Series.

When a device running Juniper Networks Junos OS with MPC7, MPC8, or MPC9 line cards installed and the system is configured for inline IP reassembly, used by MAP-E, the packet forwarding engine (PFE) will become disabled upon receipt of large packets requiring fragmentation, generating the following error messages:

[LOG: Err] MQSS(0): WO: Packet Error - Error Packets 1, Connection 29
[LOG: Err] eachip_hmcif_rx_intr_handler(7259): EA[0:0]: HMCIF Rx: Injected checksum error detected on WO response - Chunk Address 0x0
[LOG: Err] MQSS(0): DRD: RORD1: CMD reorder ID error - Command 11, Reorder ID 1838, QID 0
[LOG: Err] MQSS(0): DRD: UNROLL0: HMC chunk length error in stage 5 - Chunk Address: 0x4321f3
[LOG: Err] MQSS(0): DRD: UNROLL0: HMC chunk address error in stage 5 - Chunk Address: 0x0
[LOG: Notice] Error: /fpc/8/pfe/0/cm/0/MQSS(0)/0/MQSS_CMERROR_DRD_RORD_ENG_INT_REG_CMD_FSM_STATE_ERR (0x2203cc), scope: pfe, category: functional, severity: major, module: MQSS(0), type: DRD_RORD_ENG_INT: CMD FSM State Error
[LOG: Notice] Performing action cmalarm for error /fpc/8/pfe/0/cm/0/MQSS(0)/0/MQSS_CMERROR_DRD_RORD_ENG_INT_REG_CMD_FSM_STATE_ERR (0x2203cc) in module: MQSS(0) with scope: pfe category: functional level: major
[LOG: Notice] Performing action get-state for error /fpc/8/pfe/0/cm/0/MQSS(0)/0/MQSS_CMERROR_DRD_RORD_ENG_INT_REG_CMD_FSM_STATE_ERR (0x2203cc) in module: MQSS(0) with scope: pfe category: functional level: major
[LOG: Notice] Performing action disable-pfe for error /fpc/8/pfe/0/cm/0/MQSS(0)/0/MQSS_CMERROR_DRD_RORD_ENG_INT_REG_CMD_FSM_STATE_ERR (0x2203cc) in module: MQSS(0) with scope: pfe category: functional level: major

By continuously sending fragmented packets that cannot be reassembled, an attacker can repeatedly disable the PFE causing a sustained Denial of Service (DoS).

This issue affects Juniper Networks Junos OS:

  • 17.2 versions prior to 17.2R3-S4 on MX Series;
  • 17.3 versions prior to 17.3R3-S8 on MX Series;
  • 17.4 versions prior to 17.4R2-S10, 17.4R3-S2 on MX Series;
  • 18.1 versions prior to 18.1R3-S10 on MX Series;
  • 18.2 versions prior to 18.2R3-S3 on MX Series;
  • 18.2X75 versions prior to 18.2X75-D41, 18.2X75-D430, 18.2X75-D65 on MX Series;
  • 18.3 versions prior to 18.3R1-S7, 18.3R2-S4, 18.3R3-S1 on MX Series;
  • 18.4 versions prior to 18.4R1-S7, 18.4R2-S4, 18.4R3 on MX Series;
  • 19.1 versions prior to 19.1R1-S5, 19.1R2-S1, 19.1R3 on MX Series;
  • 19.2 versions prior to 19.2R1-S4, 19.2R2 on MX Series;
  • 19.3 versions prior to 19.3R2-S2, 19.3R3 on MX Series.

This issue is specific to inline IP reassembly, introduced in Junos OS 17.2. Versions of Junos OS prior to 17.2 are unaffected by this vulnerability.

A sample configuration for enabling inline IP reassembly is shown below:

set chassis fpc 8 pic 0 inline-services bandwidth 100g

Note: Explicitly specifying a bandwidth for tunnel traffic using inline services is not required. When a bandwidth is not specified, the maximum bandwidth supported on the PIC is automatically available for the inline services.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

This issue has been assigned CVE-2020-1655.


The following software releases have been updated to resolve this specific issue: Junos OS 17.2R3-S4, 17.3R3-S8, 17.4R2-S10, 17.4R3-S2, 18.1R3-S10, 18.2R3-S3, 18.2X75-D41, 18.2X75-D430, 18.2X75-D65, 18.3R1-S7, 18.3R2-S4, 18.3R3-S1, 18.4R1-S7, 18.4R2-S4, 18.4R3, 19.1R1-S5, 19.1R2-S1, 19.1R3, 19.2R1-S4, 19.2R2, 19.3R2-S2, 19.3R3, 19.4R1, 19.4R2, 20.1R1, and all subsequent releases.

This issue is being tracked as 1474154.

There are no available workarounds for this issue.
Software releases or updates are available for download at
Modification History:
‚Äč2020-07-08: Initial publication
2020-07-28: Only MAP-E configurations affected
CVSS Score:
5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Severity Level:
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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