CVE-2021-31386

Junos OS: When using J-Web with HTTP an attacker may retrieve encryption keys via Person-in-the-Middle attacks.

MEDIUM

5.9

CVSS Score

Published: October 19, 2021 at 06:17 PM UTC

Updated: June 17, 2026 at 03:51 AM UTC

1 product affected across 1 vendorJunos

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Severity

MEDIUM5.9

Exploit prediction

EPSS 0.7%

Description

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.

Affected

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

Junos · Juniper Networks

95%

12.3 ≤ v < 12.3R12-S2015.1 ≤ v < 15.1R7-S1118.3 ≤ v < 18.3R3-S618.4 ≤ v < 18.4R3-S1019.1 ≤ v < 19.1R3-S719.2 ≤ v < 19.2R3-S419.3 ≤ v < 19.3R3-S419.4 ≤ v < 19.4R3-S620.1 ≤ v < 20.1R3-S220.2 ≤ v < 20.2R3-S320.3 ≤ v < 20.3R3-S120.4 ≤ v < 20.4R321.1 ≤ v < 21.1R321.2 ≤ v < 21.2R212.3 12.3 r1 12.3 r10 12.3 r10-s1 12.3 r10-s2 12.3 r11 12.3 r12 12.3 r12-s1 12.3 r12-s10 12.3 r12-s11 12.3 r12-s12 12.3 r12-s13 12.3 r12-s14 12.3 r12-s15 12.3 r12-s16 12.3 r12-s17 12.3 r12-s18 12.3 r12-s19 12.3 r12-s3 12.3 r12-s4 12.3 r12-s6 12.3 r12-s8 12.3 r2 12.3 r3 12.3 r4 12.3 r5 12.3 r6 12.3 r7 12.3 r8 12.3 r9 15.1 15.1 a1 15.1 f 15.1 f1 15.1 f2 15.1 f2-s1 15.1 f2-s2 15.1 f2-s3 15.1 f2-s4 15.1 f3 15.1 f4 15.1 f5 15.1 f5-s7 15.1 f6 15.1 f6-s1 15.1 f6-s10 15.1 f6-s12 15.1 f6-s2 15.1 f6-s3 15.1 f6-s4 15.1 f6-s5 15.1 f6-s6 15.1 f6-s7 15.1 f6-s8 15.1 f6-s9 15.1 f7 15.1 r 15.1 r1 15.1 r2 15.1 r3 15.1 r4 15.1 r4-s7 15.1 r4-s8 15.1 r4-s9 15.1 r5 15.1 r5-s1 15.1 r5-s3 15.1 r5-s5 15.1 r5-s6 15.1 r6 15.1 r6-s1 15.1 r6-s2 15.1 r6-s3 15.1 r6-s4 15.1 r6-s6 15.1 r7 15.1 r7-s1 15.1 r7-s10 15.1 r7-s2 15.1 r7-s3 15.1 r7-s4 15.1 r7-s5 15.1 r7-s6 15.1 r7-s7 15.1 r7-s8 15.1 r7-s9 18.3 18.3 r1 18.3 r1-s1 18.3 r1-s2 18.3 r1-s3 18.3 r1-s4 18.3 r1-s5 18.3 r1-s6 18.3 r2 18.3 r2-s1 18.3 r2-s2 18.3 r2-s3 18.3 r2-s4 18.3 r3 18.3 r3-s1 18.3 r3-s2 18.3 r3-s3 18.3 r3-s4 18.3 r3-s5 18.4 18.4 r1 18.4 r1-s1 18.4 r1-s2 18.4 r1-s3 18.4 r1-s4 18.4 r1-s5 18.4 r1-s6 18.4 r1-s7 18.4 r2 18.4 r2-s1 18.4 r2-s2 18.4 r2-s3 18.4 r2-s4 18.4 r2-s5 18.4 r2-s6 18.4 r2-s7 18.4 r2-s8 18.4 r3 18.4 r3-s1 18.4 r3-s2 18.4 r3-s3 18.4 r3-s4 18.4 r3-s5 18.4 r3-s6 18.4 r3-s7 18.4 r3-s8 18.4 r3-s9 19.1 19.1 r1 19.1 r1-s1 19.1 r1-s2 19.1 r1-s3 19.1 r1-s4 19.1 r1-s5 19.1 r1-s6 19.1 r2 19.1 r2-s1 19.1 r2-s2 19.1 r3 19.1 r3-s1 19.1 r3-s2 19.1 r3-s3 19.1 r3-s4 19.1 r3-s5 19.1 r3-s6 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4 19.2 r1-s5 19.2 r1-s6 19.2 r2 19.2 r2-s1 19.2 r3 19.2 r3-s1 19.2 r3-s2 19.2 r3-s3 19.3 19.3 r1 19.3 r1-s1 19.3 r2 19.3 r2-s1 19.3 r2-s2 19.3 r2-s3 19.3 r2-s4 19.3 r2-s5 19.3 r3 19.3 r3-s1 19.3 r3-s2 19.3 r3-s3 19.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r1-s3 19.4 r2 19.4 r2-s1 19.4 r2-s2 19.4 r2-s3 19.4 r2-s4 19.4 r3 19.4 r3-s1 19.4 r3-s2 19.4 r3-s3 19.4 r3-s4 19.4 r3-s5 20.1 20.1 r1 20.1 r1-s1 20.1 r1-s2 20.1 r1-s3 20.1 r1-s4 20.1 r2 20.1 r2-s1 20.1 r3 20.1 r3-s1 20.2 20.2 r1 20.2 r1-s1 20.2 r1-s2 20.2 r1-s3 20.2 r2 20.2 r2-s1 20.2 r2-s2 20.2 r2-s3 20.2 r3 20.2 r3-s1 20.2 r3-s2 20.3 20.3 r1 20.3 r1-s1 20.3 r2 20.3 r2-s1 20.3 r3 20.4 20.4 r1 20.4 r1-s1 20.4 r2 20.4 r2-s1 21.1 21.1 r1 21.1 r1-s1 21.1 r2 21.2 21.2 r1 21.2 r1-s1

Affected range stops below 12.3R12-S20, so it looks safe — our inference, not a vendor statement

Affected range stops below 15.1R7-S11, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3R3-S6, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R3-S10, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R3-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.3R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.4R3-S6, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.2R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3R3-S1, 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 21.1R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.2R2, 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

https://kb.juniper.net/JSA11254

References (1)

x_refsource_CONFIRMVendor Advisory

Source: [email protected]

https://kb.juniper.net/JSA11254

CVSS

5.9MEDIUM[email protected]

Attack Vector: NETWORK
Complexity: HIGH
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: NONE
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-300CWE-311CWE-325CWE-693NVD-CWE-Other

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