CVE-2025-20209: A vulnerability in the Internet Key Exchange version 2 (IKEv2) function of Cisco IOS XR Software could allow a

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HIGH 7.5REMOTEMITIGATE

CVE-2025-20209 is a high-severity flaw (CVSS 7.5) affecting ios xr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in the Internet Key Exchange version 2 (IKEv2) function of Cisco IOS XR Software could allow an unauthenticated, remote attacker to prevent an affected device from processing any control plane UDP packets.  This vulnerability is due to improper handling of malformed IKEv2 packets. An attacker could exploit this vulnerability by sending malformed IKEv2 packets to an affected device. A successful exploit could allow the atta

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 54%)
CISA exploited list	No
Weakness	CWE-770
Published	2025-03-12
Last modified	2026-06-17

Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-03-12 16:15 UTCPublished CVE record published
2026-06-17 08:41 UTCUpdated Record last modified

cisco ios xr MITIGATE

Affected: 6.5.1 · 6.5.2 · 6.5.3 · 6.6.1 · 6.6.2 · 6.6.3 · 6.6.25 · 7.0.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.5.1

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-20209?

ios xr: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-20209 being exploited?

CVE-2025-20209 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-20209 affect?

CVE-2025-20209 affects ios xr. Severity is high (CVSS 7.5). A vulnerability in the Internet Key Exchange version 2 (IKEv2) function of Cisco IOS XR Software could allow an unauthenticated, remote attacker to prevent an affected device from processing any control plane UDP packets.  This vuln

How urgent is CVE-2025-20209?

Priority 43/100. High severity; Remotely exploitable, no login, no user action

Software pages

iOS vulnerabilities · Cisco vulnerabilities

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References

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