CVE-2021-31355

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

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.

Remediation

Solution:

  • The following software releases have been updated to resolve this specific issue: Junos OS 12.3X48-D105, 15.1X49-D220, 18.3R3-S5, 18.4R3-S9, 19.1R3-S7, 19.2R3-S3, 19.3R3-S4, 19.4R3-S6, 20.1R3, 20.2R1-S1, 20.2R2, 20.3R2, 20.4R2, 21.1R2, 21.2R1 and all subsequent releases. Additionally, after performing an upgrade to a resolved release, additional steps must be taken to ensure that all stored malicious scripts are removed from the configuration.

Workaround:

  • There are no viable workarounds for this issue.

Category

8.0
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.33%
Vendor Advisory juniper.net
Affected: Juniper Networks Junos OS
Published at:
Updated at:

References

Link Tags
https://kb.juniper.net/JSA11220 patch vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-31355?
CVE-2021-31355 has been scored as a high severity vulnerability.
How to fix CVE-2021-31355?
To fix CVE-2021-31355: The following software releases have been updated to resolve this specific issue: Junos OS 12.3X48-D105, 15.1X49-D220, 18.3R3-S5, 18.4R3-S9, 19.1R3-S7, 19.2R3-S3, 19.3R3-S4, 19.4R3-S6, 20.1R3, 20.2R1-S1, 20.2R2, 20.3R2, 20.4R2, 21.1R2, 21.2R1 and all subsequent releases. Additionally, after performing an upgrade to a resolved release, additional steps must be taken to ensure that all stored malicious scripts are removed from the configuration.
Is CVE-2021-31355 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-31355 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-31355?
CVE-2021-31355 affects Juniper Networks Junos OS.
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