Home/CVE/A Protection Mechanism Failure vulnerability in the J-Web HTTP service of Juniper Networks Junos OS allows a remote unau
CVE

CVE-2021-31386

A Protection Mechanism Failure vulnerability in the J-Web HTTP service of Juniper Networks Junos OS allows a remote unau

A Protection Mechanism Failure vulnerability in the J-Web HTTP service of Juniper Networks Junos OS allows a remote unauthenticated attacker to perform Person-in-the-Middle (PitM) attacks against the device. This issue affects: Juniper Networks Junos OS 12.3 versions prior to 12.3R12-S20.

15.1 versions prior to 15.1R7-S11.

18.3 versions prior to 18.3R3-S6.

18.4 versions prior to 18.4R3-S10.

19.1 versions prior to 19.1R3-S7.

19.2 versions prior to 19.2R3-S4.

19.3 versions prior to 19.3R3-S4.

19.4 versions prior to 19.4R3-S6.

20.1 versions prior to 20.1R3-S2.

20.2 versions prior to 20.2R3-S3.

20.3 versions prior to 20.3R3-S1.

20.4 versions prior to 20.4R3.

21.1 versions prior to 21.1R3.

21.2 versions prior to 21.2R2.

MEDIUM · CVSS 5.3 EPSS 0.00148
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  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-300Channel Accessible by Non-Endpoint
CWE-311Missing Encryption of Sensitive Data
CWE-325Missing Cryptographic Step
CWE-693Protection Mechanism Failure
▤

Affected Products & Versions

1
juniper junosall versions
▣

Scoring & Timeline

5.3
MEDIUM · CVSS v3.1 · sirt@juniper.net
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD19 Oct 2021 · 07:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://kb.juniper.net/JSA11254Vendor Advisory
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