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CVE-2021-31354

Junos OS and Junos OS Evolved: A vulnerability in the Juniper Agile License Client may allow an attacker to perform Remote Code Execution (RCE)

HIGH
8.8
CVSS Score
Published: October 19, 2021 at 06:16 PM UTC
Updated: June 17, 2026 at 03:51 AM UTC
3 products affected across 2 vendorsJunosJunos OS EvolvedJunos OS Evolved

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Severity
HIGH8.8
Exploit prediction
EPSS 0.6%

Description

An Out Of Bounds (OOB) access vulnerability in the handling of responses by a Juniper Agile License (JAL) Client in Juniper Networks Junos OS and Junos OS Evolved, configured in Network Mode (to use Juniper Agile License Manager) may allow an attacker to cause a partial Denial of Service (DoS), or lead to remote code execution (RCE). The vulnerability exists in the packet parsing logic on the client that processes the response from the server using a custom protocol. An attacker with control of a JAL License Manager, or with access to the local broadcast domain, may be able to spoof a new JAL License Manager and/or craft a response to the Junos OS License Client, leading to exploitation of this vulnerability. This issue only affects Junos systems configured in Network Mode. Systems that are configured in Standalone Mode (the default mode of operation for all systems) are not vulnerable to this issue. This issue affects: Juniper Networks Junos OS: 19.2 versions prior to 19.2R3-S3; 19.3 versions prior to 19.3R3-S3; 20.1 versions prior to 20.1R2-S2, 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2. Juniper Networks Junos OS Evolved: version 20.1R1-EVO and later versions, prior to 21.2R2-EVO. This issue does not affect Juniper Networks Junos OS versions prior to 19.2R1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos OS Evolved· Juniper
95%
20.1 r120.1 r1-s120.1 r220.1 r2-s120.1 r2-s220.1 r2-s320.1 r2-s420.1 r2-s520.1 r320.220.2 r120.2 r1-s120.2 r220.2 r2-s120.2 r320.320.3 r120.3 r1-s120.3 r1-s220.3 r1-s320.3 r220.4 r120.4 r1-s120.4 r1-s220.4 r220.4 r2-s120.4 r2-s220.4 r2-s320.4 r320.4 r3-s121.121.1 r121.1 r1-s121.1 r221.2 r121.2 r1-s1
Junos· Juniper Networks
95%
19.2 ≤ v < 19.2R3-S319.3 ≤ v < 19.3R3-S320.1 ≤ v < 20.1R2-S2, 20.1R3-S120.2 ≤ v < 20.2R3-S220.3 ≤ v < 20.3R320.4 ≤ v < 20.4R321.1 ≤ v < 21.1R219.219.2 r119.2 r1-s119.2 r1-s219.2 r1-s319.2 r1-s419.2 r1-s519.2 r1-s619.2 r219.2 r2-s119.2 r319.2 r3-s119.2 r3-s219.319.3 r119.3 r1-s119.3 r219.3 r2-s119.3 r2-s219.3 r2-s319.3 r2-s419.3 r2-s519.3 r319.3 r3-s119.3 r3-s220.120.1 r120.1 r1-s120.1 r1-s220.1 r1-s320.1 r1-s420.1 r220.1 r2-s120.1 r320.220.2 r120.2 r1-s120.2 r1-s220.2 r1-s320.2 r220.2 r2-s120.2 r2-s220.2 r2-s320.2 r320.2 r3-s120.320.3 r120.3 r1-s120.3 r220.3 r2-s120.420.4 r120.4 r1-s120.4 r220.4 r2-s121.121.1 r121.1 r1-s1
Vendor states this is fixed in 19.2R1 (unaffected)
Affected range stops below 19.2R3-S3, so it looks safe — our inference, not a vendor statement
Affected range stops below 19.3R3-S3, so it looks safe — our inference, not a vendor statement
Affected range stops below 20.1R2-S2, 20.1R3-S1, so it looks safe — our inference, not a vendor statement
Affected range stops below 20.2R3-S2, so it looks safe — our inference, not a vendor statement
Affected range stops below 20.3R3, so it looks safe — our inference, not a vendor statement
Affected range stops below 20.4R3, so it looks safe — our inference, not a vendor statement
Affected range stops below 21.1R2, so it looks safe — our inference, not a vendor statement
Junos OS Evolved· Juniper Networks
60%
v ≥ 20.1R1-EVOv < 21.2R2-EVO20.1R1-EVO
Affected range stops below 21.2R2-EVO, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://kb.juniper.net/JSA11219

CVSS

8.8HIGH[email protected]
Attack Vector
ADJACENT_NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-125

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