# What is CVE-2023-4481?

> CVE-2023-4481 is a high-severity flaw (CVSS 7.5) in Junos from Juniper, published on 1 September 2023. 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 18%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2023-4481

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 48 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.5 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:** 18% (latest exploit-likelihood forecast)
- **Published:** 1 September 2023
- **Record last updated:** 15 October 2024
- **Main product:** Junos from Juniper
- **Affected products:** 2

## What is CVE-2023-4481? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### The official description

An Improper Input Validation vulnerability in the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS).

When certain specific crafted BGP UPDATE messages are received over an established BGP session, one BGP session may be torn down with an UPDATE message error, or the issue may propagate beyond the local system which will remain non-impacted, but may affect one or more remote systems. This issue is exploitable remotely as the crafted UPDATE message can propagate through unaffected systems and intermediate BGP speakers.
Continuous receipt of the crafted BGP UPDATE messages will create a sustained Denial of Service (DoS) condition for impacted devices.

This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations.  This issue requires a remote attacker to have at least one established BGP session.
 Improper Input Validation, Denial of Service vulnerability in Juniper Networks, Inc. Junos OS (BGP, rpd modules), Juniper Networks, Inc. Junos OS Evolved (BGP, rpd modules) allows Fuzzing.This issue affects 

Junos OS: 

  *  All versions before 20.4R3-S10,
  *  from 21.1R1 through 21.*,
  *  from 21.2 before 21.2R3-S5,
  *  from 21.3 before 21.3R3-S5,
  *  from 21.4 before 21.4R3-S7 (unaffected from 21.4R3-S5, affected from 21.4R3-S6)
  *  from 22.1 before 22.1R3-S4,
  *  from 22.2 before 22.2R3-S3,
  *  from 22.3 before 22.3R3-S1,
  *  from 22.4 before 22.4R3,
  *  from 23.2 before 23.2R2.

Junos OS Evolved:

  *  All versions before 20.4R3-S10-EVO,
  *  from 21.2-EVO before 21.2R3-S7-EVO,
  *  from 21.3-EVO before 21.3R3-S5-EVO,
  *  from 21.4-EVO before 21.4R3-S5-EVO,
  *  from 22.1-EVO before 22.1R3-S4-EVO,
  *  from 22.2-EVO before 22.2R3-S3-EVO,
  *  from 22.3-EVO before 22.3R3-S1-EVO,
  *  from 22.4-EVO before 22.4R3-EVO,
  *  from 23.2-EVO before 23.2R2-EVO.

### What kind of flaw is it?

- CWE-20: Improper Input Validation

### 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: No, nobody has to do anything
- What an attacker gets: Can take it offline

Severity vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`

## Is CVE-2023-4481 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 18%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 18%, 18%, 18%, 18%, 18%, 18%, 18%.

### Timeline

- 1 September 2023: Published
- 15 October 2024: Record last updated
- 16 June 2026: Exploit likelihood jumped

### How Precursor Intelligence ranks it

CVE-2023-4481 scores **48 out of 100 (Medium)**, with the action "Plan remediation".

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-2023-4481?

The published record lists 2 products. 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, 21.1, 21.1-r1, 21.1-r1-s1, 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, 21.3, 21.3-r1, 21.3-r1-s1, 21.3-r1-s2, 21.3-r2, 21.3-r2-s1, 21.3-r2-s2, 21.3-r3 and 56 more
- [Junos OS Evolved](https://www.precursorintelligence.com/product/juniper/junos_os_evolved) by [Juniper](https://www.precursorintelligence.com/vendors/juniper) (Operating system): before 20.4, 20.4, 20.4-r1, 20.4-r1-s1, 20.4-r1-s2, 20.4-r2, 20.4-r2-s1, 20.4-r2-s2, 20.4-r2-s3, 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, 21.3, 21.3-r1, 21.3-r1-s1, 21.3-r2, 21.3-r2-s1, 21.3-r2-s2, 21.3-r3 and 56 more

## How do I fix CVE-2023-4481?

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 advisories and patch notes 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

- [kb.juniper.net](https://kb.juniper.net/JSA72510) (Vendor advisory)
- [juniper.net](https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.html) (Vendor advisory)
- [rfc-editor.org](https://www.rfc-editor.org/rfc/rfc4271) (Technical description)
- [rfc-editor.org](https://www.rfc-editor.org/rfc/rfc7606) (Technical description)

## Questions

### What is CVE-2023-4481?

CVE-2023-4481 is a high-severity flaw in Junos from Juniper, published on 1 September 2023. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

### How serious is CVE-2023-4481?

It scores 7.5 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2023-4481 is 48 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2023-4481 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 18%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2023-4481 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 90 more. The record lists 2 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2023-4481?

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-2023-4481 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.

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