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CVE-2021-31351

HIGH
Published 2021-10-19T18:16:31.714062Z
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CVSS Score

V3.1
7.5
/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base Score Metrics
Exploitability: N/A Impact: N/A

EPSS Score

v2025.03.14
0.004
probability
of exploitation in the wild

There is a 0.4% chance that this vulnerability will be exploited in the wild within the next 30 days.

Updated: 2025-06-25
Exploit Probability
Percentile: 0.591
Higher than 59.1% of all CVEs

Attack Vector Metrics

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED

Impact Metrics

Confidentiality
NONE
Integrity
NONE
Availability
HIGH

Description

An Improper Check for Unusual or Exceptional Conditions in packet processing on the MS-MPC/MS-MIC utilized by Juniper Networks Junos OS allows a malicious attacker to send a specific packet, triggering the MS-MPC/MS-MIC to reset, causing a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue only affects specific versions of Juniper Networks Junos OS on MX Series: 17.3R3-S11; 17.4R2-S13; 17.4R3 prior to 17.4R3-S5; 18.1R3-S12; 18.2R2-S8, 18.2R3-S7, 18.2R3-S8; 18.3R3-S4; 18.4R3-S7; 19.1R3-S4, 19.1R3-S5; 19.2R1-S6; 19.3R3-S2; 19.4R2-S4, 19.4R2-S5; 19.4R3-S2; 20.1R2-S1; 20.2R2-S2, 20.2R2-S3, 20.2R3; 20.3R2, 20.3R2-S1; 20.4R1, 20.4R1-S1, 20.4R2; 21.1R1; This issue does not affect any version of Juniper Networks Junos OS prior to 15.1X49-D240;

Understanding This Vulnerability

This Common Vulnerabilities and Exposures (CVE) entry provides detailed information about a security vulnerability that has been publicly disclosed. CVEs are standardized identifiers assigned by MITRE Corporation to track and catalog security vulnerabilities across software and hardware products.

The severity rating (HIGH) indicates the potential impact of this vulnerability based on the CVSS (Common Vulnerability Scoring System) framework. Higher severity ratings typically indicate vulnerabilities that could lead to more significant security breaches if exploited. Security teams should prioritize remediation efforts based on severity, exploit availability, and the EPSS (Exploit Prediction Scoring System) score, which predicts the likelihood of exploitation in the wild.

If this vulnerability affects products or systems in your infrastructure, we recommend reviewing the affected products section, checking for available patches or updates from vendors, and implementing recommended workarounds or solutions until a permanent fix is available. Organizations should also monitor security advisories and threat intelligence feeds for updates about active exploitation of this vulnerability.

Available Exploits

No exploits available for this CVE.

Related News

No news articles found for this CVE.

Affected Products

References

Workarounds

There are no viable workarounds for this issue.

Solutions

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S12, 17.4R3-S5, 18.1R3-S13, 18.3R3-S5, 18.4R3-S8, 19.1R3-S6, 19.2R1-S7, 19.2R3-S2, 19.3R2-S6, 19.3R3-S3, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R3-S1, 20.3R3, 20.4R2-S1, 20.4R3, 21.1R1-S1, 21.1R2, 21.2R1, and all subsequent releases.

Note: Only those releases listed in the PROBLEM section above are affected. This fix has also been proactively committed into other releases that are not vulnerable to this issue.

EU Vulnerability Database

Monitored by ENISA for EU cybersecurity

EU Coordination

EU Coordinated

Exploitation Status

No Known Exploitation

ENISA Analysis

Malicious code in bioql (PyPI)

Affected Products (ENISA)

juniper networks
junos os

ENISA Scoring

CVSS Score (3.1)

7.5
/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Score

0.390
probability

Data provided by ENISA EU Vulnerability Database. Last updated: October 3, 2025

GitHub Security Advisories

Community-driven vulnerability intelligence from GitHub

⚠ Unreviewed HIGH

GHSA-j3ff-rvrx-2j9x

Advisory Details

An Improper Check for Unusual or Exceptional Conditions in packet processing on the MS-MPC/MS-MIC utilized by Juniper Networks Junos OS allows a malicious attacker to send a specific packet, triggering the MS-MPC/MS-MIC to reset, causing a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue only affects specific versions of Juniper Networks Junos OS on MX Series: 17.3R3-S11; 17.4R2-S13; 17.4R3 prior to 17.4R3-S5; 18.1R3-S12; 18.2R2-S8, 18.2R3-S7, 18.2R3-S8; 18.3R3-S4; 18.4R3-S7; 19.1R3-S4, 19.1R3-S5; 19.2R1-S6; 19.3R3-S2; 19.4R2-S4, 19.4R2-S5; 19.4R3-S2; 20.1R2-S1; 20.2R2-S2, 20.2R2-S3, 20.2R3; 20.3R2, 20.3R2-S1; 20.4R1, 20.4R1-S1, 20.4R2; 21.1R1; This issue does not affect any version of Juniper Networks Junos OS prior to 15.1X49-D240;

CVSS Scoring

CVSS Score

7.5

Advisory provided by GitHub Security Advisory Database. Published: May 24, 2022, Modified: May 24, 2022

References

Published: 2021-10-19T18:16:31.714062Z
Last Modified: 2024-09-17T01:26:12.258Z
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