CVE-2021-31355

Junos OS: Stored Cross-Site Scripting (XSS) vulnerability in captive portal

MEDIUM

5.4

CVSS Score

Published: October 19, 2021 at 06:16 PM UTC

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

1 product affected across 1 vendorJunos

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Severity

MEDIUM5.4

Exploit prediction

EPSS 0.8%

Description

A persistent cross-site scripting (XSS) vulnerability in the captive portal graphical user interface of Juniper Networks Junos OS may allow a remote authenticated user to inject web script or HTML and steal sensitive data and credentials from a web administration session, possibly tricking a follow-on administrative user to perform administrative actions on the device. This issue affects Juniper Networks Junos OS: All versions, including the following supported releases: 12.3X48 versions prior to 12.3X48-D105; 15.1X49 versions prior to 15.1X49-D220; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R3-S9; 19.1 versions prior to 19.1R3-S7; 19.2 versions prior to 19.2R3-S3; 19.3 versions prior to 19.3R3-S4; 19.4 versions prior to 19.4R3-S6; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R1-S1, 20.2R2; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R2; 21.1 versions prior to 21.1R2.

Affected

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

Junos · Juniper Networks

95%

12.3X48 ≤ v < 12.3X48-D10515.1X49 ≤ v < 15.1X49-D22018.3 ≤ v < 18.3R3-S518.4 ≤ v < 18.4R3-S919.1 ≤ v < 19.1R3-S719.2 ≤ v < 19.2R3-S319.3 ≤ v < 19.3R3-S419.4 ≤ v < 19.4R3-S620.1 ≤ v < 20.1R320.2 ≤ v < 20.2R1-S1, 20.2R220.3 ≤ v < 20.3R220.4 ≤ v < 20.4R221.1 ≤ v < 21.1R212.3X4812.3x4812.3x48 d10 12.3x48 d100 12.3x48 d15 12.3x48 d20 12.3x48 d25 12.3x48 d30 12.3x48 d35 12.3x48 d40 12.3x48 d45 12.3x48 d50 12.3x48 d51 12.3x48 d55 12.3x48 d60 12.3x48 d6512.3x48 d6612.3x48 d70 12.3x48 d7512.3x48 d8012.3x48 d85 12.3x48 d90 12.3x48 d95 15.1X4915.1x4915.1x49 d10 15.1x49 d100 15.1x49 d110 15.1x49 d120 15.1x49 d13015.1x49 d13115.1x49 d140 15.1x49 d15 15.1x49 d150 15.1x49 d160 15.1x49 d170 15.1x49 d180 15.1x49 d190 15.1x49 d20 15.1x49 d200 15.1x49 d210 15.1x49 d25 15.1x49 d30 15.1x49 d35 15.1x49 d40 15.1x49 d45 15.1x49 d50 15.1x49 d55 15.1x49 d60 15.1x49 d65 15.1x49 d70 15.1x49 d75 15.1x49 d80 15.1x49 d90 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 r3 18.3 r3-s1 18.3 r3-s2 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 r3 18.4 r3-s1 18.4 r3-s2 18.4 r3-s3 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 r2 19.1 r2-s1 19.1 r3 19.1 r3-s1 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4 19.2 r2 19.2 r2-s1 19.3 19.3 r1 19.3 r1-s1 19.3 r2 19.3 r2-s1 19.3 r2-s2 19.3 r2-s3 19.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r2 19.4 r2-s1 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 r2-s2 20.2 20.2 r1 20.2 r2 20.3 20.3 r1 20.3 r1-s1 20.4 20.4 r1 20.4 r1-s1 21.1 21.1 r1 21.1 r1-s1

Affected range stops below 12.3X48-D105, so it looks safe — our inference, not a vendor statement

Affected range stops below 15.1X49-D220, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3R3-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R3-S9, 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-S3, 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, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.2R1-S1, 20.2R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.4R2, 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

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/JSA11220

References (1)

x_refsource_CONFIRMPatchVendor Advisory

Source: [email protected]

https://kb.juniper.net/JSA11220

CVSS

5.4MEDIUM[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: LOW
User Interaction: REQUIRED
Scope: CHANGED
Confidentiality: LOW
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-79

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