CVE-2021-0269 Junos OS: J-Web can be compromised through reflected client-side HTTP parameter pollution attacks.
Attackers can manipulate J-Web parameters to bypass security controls, exfiltrate data, or redirect users via HTTP parameter pollution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2021-0269?
CVE-2021-0269 is a high-severity vulnerability in Juniper Junos, published on 22 Apr 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
The improper handling of client-side parameters in J-Web of Juniper Networks Junos OS allows an attacker to perform a number of different malicious actions against a target device when a user is authenticated to J-Web. An attacker may be able to supersede existing parameters, including hardcoded parameters within the HTTP/S session, access and exploit variables, bypass web application firewall rules or input validation mechanisms, and otherwise alter and modify J-Web's normal behavior. An attacker may be able to transition victims to malicious web services, or exfiltrate sensitive information from otherwise secure web forms. This issue affects: Juniper Networks Junos OS: All versions prior to 17.4R3-S3; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S6; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2.
Weakness: CWE-233
Which versions are affected by CVE-2021-0269?
It affects 1 product.
Products include Juniper Junos.
How do I fix CVE-2021-0269?
No fix has been published for CVE-2021-0269 yet. Limit exposure of the affected software until one is available.
Is CVE-2021-0269 being exploited?
There is no known exploitation of CVE-2021-0269 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos
- CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification
- CVE-2020-1631 Juniper Junos OS Path Traversal
- CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization
- CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function
- CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification
Sources
Also known as GHSA-jf9f-q955-wjwx.