CVE-2024-21620: Junos OS: SRX Series and EX Series: J-Web doesn't sufficiently sanitize input to prevent XSS

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-01-25 · updated 2026-06-17
Weakness: CWE-79

Description

An Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in J-Web of Juniper Networks Junos OS on SRX Series and EX Series allows an attacker to construct a URL that when visited by another user enables the attacker to execute commands with the target's permissions, including an administrator. A specific invocation of the emit_debug_note method in webauth_operation.php will echo back the data it receives. This issue affects Juniper Networks Junos OS on SRX Series and EX Series: * All versions earlier than 20.4R3-S10; * 21.2 versions earlier than 21.2R3-S8; * 21.4 versions earlier than 21.4R3-S6; * 22.1 versions earlier than 22.1R3-S5; * 22.2 versions earlier than 22.2R3-S3; * 22.3 versions earlier than 22.3R3-S2; * 22.4 versions earlier than 22.4R3-S1; * 23.2 versions earlier than 23.2R2; * 23.4 versions earlier than 23.4R2.

Affected products

Juniper Junos OS: before 20.4; 20.4, 20.4-r1, 20.4-r1-s1, 20.4-r2, 20.4-r2-s1, 20.4-r2-s2 (+82) — fixed in 20.4

How to fix

Upgrade to a fixed version: Juniper Junos OS 20.4. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2024-21620 or the next vulnerability affects your stack