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NVD / CVE Program· CNA juniper

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

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1% (FIRST EPSS); higher than 63.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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 L2TP, MAP-E, GRE, and IPIP, 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.

MediumCVSS 5.3 · v3.1—No exploit No fix recorded
Published
Jul 17, 2020
Updated
Jun 16, 2026
EPSS
1.0% · 63th percentile
CWE
—

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.0%

CNA vs NVD score

NVD
5.3
CNA · juniper
5.3
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
juniperjunos
junipermx10
junipermx10000
junipermx10003
junipermx104
junipermx150
junipermx2008
junipermx2010
junipermx2020
junipermx204
junipermx240
junipermx40

and 4 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • juniper junos17.2
  • juniper junos17.3
  • juniper junos17.4
  • juniper junos18.1
  • juniper junos18.2
  • juniper junos18.2x75
  • juniper junos18.3
  • juniper junos18.4
  • juniper junos19.1
  • juniper junos19.2
  • juniper junos19.3

Versions reported by the vendor

Affected version ranges reported by the assigning authority (juniper). Independent of NVD's CPE analysis and usually ahead of it.

  • Juniper Networks Junos OS

    • unspecified and later · before 17.2not affected
    • 17.2 and later · before 17.2R3-S4affected
    • 17.3 and later · before 17.3R3-S8affected
    • 17.4 and later · before 17.4R2-S10, 17.4R3-S2affected
    • 18.1 and later · before 18.1R3-S10affected
    • 18.2 and later · before 18.2R3-S3affected
    • 18.2X75 and later · before 18.2X75-D41, 18.2X75-D430, 18.2X75-D65affected
    • 18.3 and later · before 18.3R1-S7, 18.3R2-S4, 18.3R3-S1affected
    • 18.4 and later · before 18.4R1-S7, 18.4R2-S4, 18.4R3affected
    • 19.1 and later · before 19.1R1-S5, 19.1R2-S1, 19.1R3affected

Same product

juniper: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-36845Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to control an important environment variableKEV
    98Now
  • CVE-2023-36846Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary filesKEV
    79This week
  • CVE-2023-36844Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variablesKEV
    78This week

Published before and after this one in the same product

  • ← EarlierCVE-2020-1653Jul 17, 2020 · Junos OS: Kernel crash (vmcore) or FPC crash due to mbuf leak
    30Monitor
  • ← EarlierCVE-2020-1654Jul 17, 2020 · Junos OS: SRX Series: processing a malformed HTTP message when ICAP redirect service is enabled may can lead to flowd process crash or remote code execution
    40Plan
  • Later →CVE-2020-1656Oct 16, 2020 · Junos OS: When a DHCPv6 Relay-Agent is configured upon receipt of a specific DHCPv6 client message, Remote Code Execution may occur.
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
low · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
Low

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records