CVE-2021-31373

Name: CVE-2021-31373
Creator: NVD / NIST
Published: 2021-10-19T19:15:10.4+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 0.78%

Last modified Jun 17, 2026

CVE-2021-31373 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. A persistent Cross-Site Scripting (XSS) vulnerability in Juniper Networks Junos OS on SRX Series, J-Web interface may allow a remote authenticated user to inject persistent and malicious scripts. An attacker can exploit this vulnerability to steal sensitive data and credentials from a web administration session, or hijack another user's active session to perform administrative actions. EPSS estimates a 0.78% chance of exploitation in the next 30 days.

Description

A persistent Cross-Site Scripting (XSS) vulnerability in Juniper Networks Junos OS on SRX Series, J-Web interface may allow a remote authenticated user to inject persistent and malicious scripts. An attacker can exploit this vulnerability to steal sensitive data and credentials from a web administration session, or hijack another user's active session to perform administrative actions. This issue affects: Juniper Networks Junos OS on SRX Series: 18.2 versions prior to 18.2R3-S8; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R3-S8; 19.1 versions prior to 19.1R3-S5; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R1-S4, 19.4R2-S4, 19.4R3-S3; 20.1 versions prior to 20.1R2-S2, 20.1R3; 20.2 versions prior to 20.2R3-S1; 20.3 versions prior to 20.3R2-S1, 20.3R3.

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.78%

51.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Juniper	Junos	18.2	—
Juniper	Junos	18.3	—
Juniper	Junos	18.4	—
Juniper	Junos	19.1	—
Juniper	Junos	19.2	—
Juniper	Junos	19.3	—
Juniper	Junos	19.4	R1
Juniper	Junos	20.1	R1
Juniper	Junos	20.2	R1
Juniper	Junos	20.3	R1

References

https://kb.juniper.net/JSA11238Vendor Advisory
https://kb.juniper.net/JSA11238Vendor Advisory

Timeline

Published: Oct 19, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31373?

How severe is CVE-2021-31373?

CVE-2021-31373 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.78% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31373?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31373?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST