Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.64% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2021
CVE-2021-0222High confidence
Junos OS: Upon receipt of certain protocol packets with invalid payloads a self-propagating Denial of Service may occur.
Juniper Networks · Junos OS
7.4HighCVSS 3.1
Within 7 days
Patch availableHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Juniper Networks Junos OS and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available01
What, why and how
A vulnerability in Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) to the device by sending certain crafted protocol packets from an adjacent device with invalid payloads to the device. These crafted packets, which should be discarded, are instead replicated and sent to the RE. Over time, a Denial of Service (DoS) occurs. Continued receipt of these crafted protocol packets will cause an extended Denial of Service (DoS) condition, which may cause wider traffic impact due to protocol flapping. An indication of compromise is to check "monitor interface traffic" on the ingress and egress port packet counts. For each ingress packet, two duplicate packets are seen on egress. This issue can be triggered by IPv4 and IPv6 packets. This issue affects all traffic through the device. This issue affects: Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D53 on EX4300, QFX3500, QFX5100, EX4600; 15.1 versions prior to 15.1R7-S6 on EX4300, QFX3500, QFX5100, EX4600; 16.1 versions prior to 16.1R7-S7 on EX4300, QFX5100, EX4600; 17.1 versions prior to 17.1R2-S11 on EX4300, QFX5100, EX4600; 17.1 versions prior to 117.1R3-S2 on EX4300; 17.2 versions prior to 17.2R1-S9 on EX4300; 17.2 versions prior to 17.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.4 versions prior to 17.4R2-S9, 17.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 18.1 versions prior to 18.1R3-S9 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.2 versions prior to 18.2R2-S7 on EX4300; 18.2 versions prior to 18.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.3 versions prior to 18.3R2-S3, on EX4300; 18.3 versions prior to 18.3R1-S7, 18.3R3-S1 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.1 versions prior to 19.1R1-S4, 19.1R2-S1, 19.1R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.2 versions prior to 19.2R1-S4, 19.2R2 on EX4300; 19.2 versions prior to 19.2R1-S3, 19.2R2 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.3 versions prior to 19.3R2-S1, 19.3R3 on EX4300; 19.3 versions prior to 19.3R1-S1, 19.3R2, 19.3R3 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400;
What
A vulnerability in Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) to the device by sending certain crafted protocol packets from an adjacent device with invalid payloads to the device. These crafted packets, which should be discarded, are instead replicated and sent to the RE. Over time, a Denial of Service (DoS) occurs. Continued receipt of these crafted protocol packets will cause an extended Denial of Service (DoS) condition, which may cause wider traffic impact due to protocol flapping. An indication of compromise is to check "monitor interface traffic" on the ingress and egress port packet counts. For each ingress packet, two duplicate packets are seen on egress. This issue can be triggered by IPv4 and IPv6 packets. This issue affects all traffic through the device. This issue affects: Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D53 on EX4300, QFX3500, QFX5100, EX4600; 15.1 versions prior to 15.1R7-S6 on EX4300, QFX3500, QFX5100, EX4600; 16.1 versions prior to 16.1R7-S7 on EX4300, QFX5100, EX4600; 17.1 versions prior to 17.1R2-S11 on EX4300, QFX5100, EX4600; 17.1 versions prior to 117.1R3-S2 on EX4300; 17.2 versions prior to 17.2R1-S9 on EX4300; 17.2 versions prior to 17.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.4 versions prior to 17.4R2-S9, 17.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 18.1 versions prior to 18.1R3-S9 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.2 versions prior to 18.2R2-S7 on EX4300; 18.2 versions prior to 18.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.3 versions prior to 18.3R2-S3, on EX4300; 18.3 versions prior to 18.3R1-S7, 18.3R3-S1 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.1 versions prior to 19.1R1-S4, 19.1R2-S1, 19.1R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.2 versions prior to 19.2R1-S4, 19.2R2 on EX4300; 19.2 versions prior to 19.2R1-S3, 19.2R2 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.3 versions prior to 19.3R2-S1, 19.3R3 on EX4300; 19.3 versions prior to 19.3R1-S1, 19.3R2, 19.3R3 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400;
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
What
A vulnerability in Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) to the device by sending certain crafted protocol packets from an adjacent device with invalid payloads to the device. These crafted packets, which should be discarded, are instead replicated and sent to the RE. Over time, a Denial of Service (DoS) occurs. Continued receipt of these crafted protocol packets will cause an extended Denial of Service (DoS) condition, which may cause wider traffic impact due to protocol flapping. An indication of compromise is to check "monitor interface traffic" on the ingress and egress port packet counts. For each ingress packet, two duplicate packets are seen on egress. This issue can be triggered by IPv4 and IPv6 packets. This issue affects all traffic through the device. This issue affects: Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D53 on EX4300, QFX3500, QFX5100, EX4600; 15.1 versions prior to 15.1R7-S6 on EX4300, QFX3500, QFX5100, EX4600; 16.1 versions prior to 16.1R7-S7 on EX4300, QFX5100, EX4600; 17.1 versions prior to 17.1R2-S11 on EX4300, QFX5100, EX4600; 17.1 versions prior to 117.1R3-S2 on EX4300; 17.2 versions prior to 17.2R1-S9 on EX4300; 17.2 versions prior to 17.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.4 versions prior to 17.4R2-S9, 17.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 18.1 versions prior to 18.1R3-S9 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.2 versions prior to 18.2R2-S7 on EX4300; 18.2 versions prior to 18.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.3 versions prior to 18.3R2-S3, on EX4300; 18.3 versions prior to 18.3R1-S7, 18.3R3-S1 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.1 versions prior to 19.1R1-S4, 19.1R2-S1, 19.1R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.2 versions prior to 19.2R1-S4, 19.2R2 on EX4300; 19.2 versions prior to 19.2R1-S3, 19.2R2 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.3 versions prior to 19.3R2-S1, 19.3R3 on EX4300; 19.3 versions prior to 19.3R1-S1, 19.3R2, 19.3R3 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400;
Why
The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.
How
An attacker operating through an adjacent network may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- an adjacent network → vulnerable operation → disrupt the affected service
- Attack surface
- Adjacent
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Changed: exploitation can affect a different security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-16 ↗
CWE-16. Open the MITRE definition for the exact weakness description.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Action
- Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 15 Jan 2021 · Last source change 16 Sept 2024, 20:03 UTC · CWE-16
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2021-2841
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.