What is CVE-2025-20142?A high-severity flaw in IOS XR, explained.
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.
Published 12 March 2025. Record last updated 1 August 2025. We keep this page's data up to date.
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.
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-20Improper Input Validation
How an attack on it works
Read straight from its severity rating, translated out of the shorthand.
- Where an attacker can beAnywhere on the internet
- How hard it is to pull offEasy: no special conditions
- Login needed firstNo login needed
- Does someone have to clickNo, nobody has to do anything
- What an attacker getsCan 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.
Timeline
- Published
- Record last updated
CVE-2025-20142 scores 48. Action: Plan remediation.
We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:
- Evidence it is being exploitedBiggest factor
- How severe it isStrong factor
- How widely exposed it isSmaller factor
- Threat activity around itSmaller factor
85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.
When CVE-2025-20142 matches software you track, it lands in your list with its score and the reasons behind it.
See your own ranked list →Who is affected by CVE-2025-20142? One product.
The published record lists 1 product from 1 vendor. If you run one of these, check your version, then go to the fix below.
How do I fix CVE-2025-20142? Four steps.
- Check whether you run itCompare 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.
- Apply the vendor’s fixInstall the update named in the vendor’s advisory. We’ve put the advisory first in the list.
- If you can’t patch todayFollow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
- Keep an eye on itTrack 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.
Does CVE-2025-20142 affect you? We'll keep checking.
Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.
- Tell us what you runPick your software from a list, or let us work it out from your website.
- We match it to every flawOver 400,000 published flaws, checked against your list.
- Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
- Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
Free plan, no card needed. Nothing to install.
1 new flaw affects software Acme tracks
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 ...
- Matched to
- IOS XR on Acme's software list
- What to do
- Plan in the vendor’s update
Sent to the alert recipients Acme chose. Also in the app and to Acme's webhook.
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.
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.
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.
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.
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.