# What is CVE-2024-21620? > CVE-2024-21620 is a medium-severity flaw (CVSS 6.1) in Junos from Juniper, published on 25 January 2024. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 0.9%. If you run an affected version, plan in the vendor’s fix. Canonical page: https://www.precursorintelligence.com/what-is/cve-2024-21620 ## At a glance - **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle. - **Precursor Intelligence risk score:** 81 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes. - **Severity:** Medium (CVSS 6.1 out of 10) - **Known to be exploited:** No, not on the list of flaws known to be exploited today - **Chance of use in the next 30 days:** 0.9% (latest exploit-likelihood forecast) - **Published:** 25 January 2024 - **Record last updated:** 17 June 2026 - **Main product:** Junos from Juniper - **Affected products:** 1 ## What is CVE-2024-21620? In plain terms It can be attacked from anywhere on the internet without logging in, but a person has to take an action first. If it works, the attacker can read some data and change some data. ### The official 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. ### What kind of flaw is it? - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') ### How an attack on it works - Where an attacker can be: Anywhere on the internet - How hard it is to pull off: Easy: no special conditions - Login needed first: No login needed - Does someone have to click: Yes, a person has to take an action - What an attacker gets: Can read some data and change some data Severity vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N` ## Is CVE-2024-21620 being exploited? Not that we know of It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.9%. That can change at any time, which is why we keep watching. Exploit likelihood over the last 7 days: 0.9%, 0.9%, 0.9%, 0.9%, 0.9%, 0.9%, 0.9%. ### Timeline - 25 January 2024: Published - 17 June 2026: Record last updated ### How Precursor Intelligence ranks it CVE-2024-21620 scores **81 out of 100 (High)**, with the action "Emergency patch". Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less: - Evidence it is being exploited: biggest factor - How severe it is: strong factor - How widely exposed it is: smaller factor - Threat activity around it: smaller factor 85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it. ## Who is affected by CVE-2024-21620? The published record lists 1 product. Versions are as published: "before 20.4" means every version up to, but not including, 20.4. - [Junos](https://www.precursorintelligence.com/product/juniper/junos) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Operating system): before 20.4, 20.4, 20.4-r1, 20.4-r1-s1, 20.4-r2, 20.4-r2-s1, 20.4-r2-s2, 20.4-r3, 20.4-r3-s1, 20.4-r3-s2, 20.4-r3-s3, 20.4-r3-s4, 20.4-r3-s5, 20.4-r3-s6, 20.4-r3-s7, 20.4-r3-s8, 20.4-r3-s9, 21.2, 21.2-r1, 21.2-r1-s1, 21.2-r1-s2, 21.2-r2, 21.2-r2-s1, 21.2-r2-s2, 21.2-r3, 21.2-r3-s1, 21.2-r3-s2, 21.2-r3-s3, 21.2-r3-s4, 21.2-r3-s5, 21.2-r3-s6, 21.2-r3-s7, 21.4, 21.4-r1, 21.4-r1-s1, 21.4-r1-s2, 21.4-r2, 21.4-r2-s1, 21.4-r2-s2, 21.4-r3 and 49 more ## How do I fix CVE-2024-21620? 1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list. 2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list. 3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in. 4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood. ### References - [supportportal.juniper.net](https://supportportal.juniper.net/JSA76390) (Vendor advisory) ## Questions ### What is CVE-2024-21620? CVE-2024-21620 is a medium-severity flaw in Junos from Juniper, published on 25 January 2024. It can be attacked from anywhere on the internet without logging in, but a person has to take an action first. If it works, the attacker can read some data and change some data. ### How serious is CVE-2024-21620? It scores 6.1 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2024-21620 is 81 out of 100, which is High. Its action is "Emergency patch". No sign of exploitation and a low forecast. Patch it in your normal update cycle. ### Is CVE-2024-21620 being exploited? It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.9%. That can change at any time, which is why we keep watching. ### Which versions does CVE-2024-21620 affect? For Junos from Juniper: before 20.4, 20.4, 20.4-r1, 20.4-r1-s1, 20.4-r2, 20.4-r2-s1 and 83 more. ### How do I fix CVE-2024-21620? Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. ## Does CVE-2024-21620 affect you? Precursor Intelligence keeps checking for you: - **Tell us what you run.** Pick your software from a list, or let us work it out from your website. - **We match it to every flaw.** Over 400,000 published flaws, checked against your list. - **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it. - **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools. Start free (no card, nothing to install): https://www.precursorintelligence.com/register Book a demo: https://www.precursorintelligence.com/contact