# What is CVE-2025-20142?

> CVE-2025-20142 is a high-severity flaw (CVSS 8.6) in IOS XR from Cisco, published on 12 March 2025. 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 0.5%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2025-20142

## 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:** 48 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 8.6 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:** 0.5% (latest exploit-likelihood forecast)
- **Published:** 12 March 2025
- **Record last updated:** 1 August 2025
- **Main product:** IOS XR from Cisco
- **Affected products:** 1

## What is CVE-2025-20142? 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

A vulnerability in the IPv4 access control list (ACL) feature and quality of service (QoS) policy feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact High-Performance Routers, and ASR 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause a line card to reset, resulting in a denial of service (DoS) condition.

This vulnerability is due to the incorrect handling of malformed IPv4 packets that are received on line cards where the interface has either an IPv4 ACL or QoS policy applied. An attacker could exploit this vulnerability by sending crafted IPv4 packets through an affected device. A successful exploit could allow the attacker to cause network processor errors, resulting in a reset or shutdown of the network process. Traffic over that line card would be lost while the line card reloads.
Note: This vulnerability has predominantly been observed in Layer 2 VPN (L2VPN) environments where an IPv4 ACL or QoS policy has been applied to the bridge virtual interface. Layer 3 configurations where the interface has either an IPv4 ACL or QoS policy applied are also affected, though the vulnerability has not been observed.

### 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:C/C:N/I:N/A:H`

## Is CVE-2025-20142 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 0.5%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 0.5%, 0.5%, 0.5%, 0.5%, 0.5%, 0.5%, 0.5%.

### Timeline

- 12 March 2025: Published
- 1 August 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2025-20142 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-2025-20142?

The published record lists 1 product.

- [IOS XR](https://www.precursorintelligence.com/product/cisco/ios_xr) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): 6.7.2, 6.7.3, 6.7.35, 6.8.1, 6.8.2, 6.9.1, 6.9.2, 7.1.2, 7.1.3, 7.1.15, 7.1.25, 7.3.1, 7.3.2, 7.3.3, 7.3.4, 7.3.5, 7.4.1, 7.4.2, 7.5.1, 7.5.2, 7.5.3, 7.5.4, 7.5.5, 7.6.1, 7.6.2, 7.7.1, 7.7.2, 7.8.1, 7.8.2, 7.8.22, 7.8.23, 7.9.1, 7.9.2, 7.10.1

## How do I fix CVE-2025-20142?

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

- [sec.cloudapps.cisco.com](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipv4uni-LfM3cfBu) (Vendor advisory)
- [blog.apnic.net](https://blog.apnic.net/2024/09/02/crafting-endless-as-paths-in-bgp/) (Technical description)

## Questions

### What is CVE-2025-20142?

CVE-2025-20142 is a high-severity flaw in IOS XR from Cisco, published on 12 March 2025. 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-2025-20142?

It scores 8.6 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2025-20142 is 48 out of 100, which is Medium. Its action is "Plan remediation". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

### Is CVE-2025-20142 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 0.5%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2025-20142 affect?

For IOS XR from Cisco: 6.7.2, 6.7.3, 6.7.35, 6.8.1, 6.8.2, 6.9.1 and 28 more.

### How do I fix CVE-2025-20142?

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-2025-20142 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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