CVE-2020-1603: Junos OS: Improper handling of specific IPv6 packets sent by clients eventually kernel crash (vmcore) the device.
Noroxi assessment
Priority: Monitor (action score 34/100)
- 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: 1.4% (FIRST EPSS); higher than 72.5% 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
Specific IPv6 packets sent by clients processed by the Routing Engine (RE) are improperly handled. These IPv6 packets are designed to be blocked by the RE from egressing the RE. Instead, the RE allows these specific IPv6 packets to egress the RE, at which point a mbuf memory leak occurs within the Juniper Networks Junos OS device. This memory leak eventually leads to a kernel crash (vmcore), or the device hanging and requiring a power cycle to restore service, creating a Denial of Service (DoS) condition. During the time where mbufs are rising, yet not fully filled, some traffic from client devices may begin to be black holed. To be black holed, this traffic must match the condition where this traffic must be processed by the RE. Continued receipt and attempted egress of these specific IPv6 packets from the Routing Engine (RE) will create an extended Denial of Service (DoS) condition. Scenarios which have been observed are: 1. In a single chassis, single RE scenario, the device will hang without vmcore, or a vmcore may occur and then hang. In this scenario the device needs to be power cycled. 2. In a single chassis, dual RE scenario, the device master RE will fail over to the backup RE. In this scenario, the master and the backup REs need to be reset from time to time when they vmcore. There is no need to power cycle the device. 3. In a dual chassis, single RE scenario, the device will hang without vmcore, or a vmcore may occur and then hang. In this scenario, the two chassis' design relies upon some type of network level redundancy - VRRP, GRES, NSR, etc. - 3.a In a commanded switchover, where nonstop active routing (NSR) is enabled no session loss is observed. 4. In a dual chassis, dual chassis scenario, rely upon the RE to RE failover as stated in the second scenario. In the unlikely event that the device does not switch RE to RE gracefully, then the fallback position is to the network level services scenario in the third scenario. This issue affects: Juniper Networks Junos OS 16.1 versions prior to 16.1R7-S6; 16.1 version 16.1X70-D10 and later; 16.2 versions prior to 16.2R2-S11; 17.1 versions prior to 17.1R2-S11, 17.1R3-S1; 17.2 versions prior to 17.2R1-S9, 17.2R2-S8, 17.2R3-S3; 17.3 versions prior to 17.3R3-S6; 17.4 versions prior to 17.4R2-S9, 17.4R3; 18.1 versions prior to 18.1R3-S7; 18.2 versions prior to 18.2R3-S2; 18.2X75 versions prior to 18.2X75-D50, 18.2X75-D410; 18.3 versions prior to 18.3R1-S6, 18.3R2-S2, 18.3R3; 18.4 versions prior to 18.4R1-S6, 18.4R2-S2, 18.4R3; 19.1 versions prior to 19.1R1-S3, 19.1R2; 19.2 versions prior to 19.2R1-S2, 19.2R2. This issue does not affect releases prior to Junos OS 16.1R1.
- Published
- Jan 15, 2020
- Updated
- Jun 16, 2026
- EPSS
- 1.4% · 72th percentile
- CWE
- CWE-710
Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 34 / 40 · 8.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.4%
CNA vs NVD score
- NVD
- 8.6
- CNA · juniper
- 8.6
- 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
If any of these changes, we'll tell you in the daily email digest.
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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.
We use this product, ask for helpAffected 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.
| Vendor | Product | CPE |
|---|---|---|
| juniper | junos | cpe:2.3:o:juniper:junos |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- juniper junos16.1
- juniper junos16.1x70
- juniper junos16.2
- juniper junos17.1
- 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
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
- 16.1 and later · before 16.1R7-S6affected
- 16.2 and later · before 16.2R2-S11affected
- 17.1 and later · before 17.1R2-S11, 17.1R3-S1affected
- 17.2 and later · before 17.2R1-S9, 17.2R2-S8, 17.2R3-S3affected
- 17.3 and later · before 17.3R3-S6affected
- 17.4 and later · before 17.4R2-S9, 17.4R3affected
- 18.1 and later · before 18.1R3-S7affected
- 18.2 and later · before 18.2R3-S2affected
- 18.2X75 and later · before 18.2X75-D50, 18.2X75-D410affected
- 18.3 and later · before 18.3R1-S6, 18.3R2-S2, 18.3R3affected
Same product
juniper: all recordsOther 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 variableKEV98Now
- CVE-2023-36846Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary filesKEV79This week
- CVE-2023-36844Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variablesKEV78This week
Published before and after this one in the same product
- ← EarlierCVE-2020-1601Jan 15, 2020 · Junos OS: Upon receipt of certain types of malformed PCEP packets the pccd process may crash.30Monitor
- ← EarlierCVE-2020-1602Jan 15, 2020 · Junos OS and Junos OS Evolved: A vulnerability in JDHCPD allows an attacker to send crafted IPv4 packets may take over the code execution of the JDHCPD process.35Monitor
- Later →CVE-2020-1604Jan 15, 2020 · Junos OS: EX4300/EX4600/QFX3500/QFX5100 Series: Stateless IP firewall filter may fail to evaluate certain packets21Monitor
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 researchersFinders, 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
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-710 · Improper Adherence to Coding StandardsCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
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)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.