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iOSOperating system · Cisco

CVE-2025-20154

HIGH · 8.6 CVSS v3.1 Published 2025-05-07
Fix available
A fix is available. Upgrade to after 17.2.3 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the Two-Way Active Measurement Protocol (TWAMP) server feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. For Cisco IOS XR Software, this vulnerability could cause the ipsla_ippm_server process to reload unexpectedly if debugs are enabled. This vulnerability is due to out-of-bounds array access when processing specially crafted TWAMP control packets. An attacker could exploit this vulnerability by sending crafted TWAMP control packets to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Note: For Cisco IOS XR Software, only the ipsla_ippm_server process reloads unexpectedly and only when debugs are enabled. The vulnerability details for Cisco IOS XR Software are as follows:    Security Impact Rating (SIR): Low    CVSS Base Score: 3.7    CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A vulnerability in the TWAMP server feature of Cisco IOS Software and Cisco IOS XE Software allows an unauthenticated remote attacker to cause device reload (DoS) by sending specially crafted TWAMP control packets. The root cause is out-of-bounds array access when processing these packets. For Cisco IOS XR, only the ipsla_ippm_server process crashes, and only when debugs are enabled.

MitigationApply Cisco security updates when available. For IOS XR, disable debugs on the ipsla_ippm_server process as a workaround. Consider disabling the TWAMP server feature if not required.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
iOSOperating system
Affected:<= 15.9\(3\)m11
Ios XeOperating system
Affected:>= 16.6.1, <= 17.2.3
Ios XrOperating system
Affected:= 6.5.1= 6.5.2= 6.5.3= 6.5.15= 6.5.25= 6.5.26= 6.5.28= 6.5.29= 6.5.31= 6.5.32= 6.5.33= 6.5.35

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Cisco software version
    Run 'show version' on the device console or via SSH to retrieve the installed IOS, IOS XE, or IOS XR version string.
    Affected if The version falls within any of these ranges: iOS <= 15.9(3)m11, IOS XE >= 16.6.1 and <= 17.2.3, or IOS XR version 6.5.1, 6.5.2, 6.5.3, 6.5.15, 6.5.25, 6.5.26, 6.5.28, 6.5.29, 6.5.31, 6.5.32, 6.5.33, or 6.5.35.
  2. Verify if TWAMP server is configured
    Run 'show running-config | include twamp' or 'show twamp server status' (if available on the platform) to check whether the TWAMP server feature is enabled in the current configuration.
    Affected if TWAMP server is enabled and the device is running a vulnerable software version.
  3. Check for active TWAMP listener
    Run 'show tcp brief | include twamp' or 'show udp brief | include twamp' to see if the device is listening on TWAMP ports (typically UDP port 862).
    Affected if The device has an active TWAMP server listener and runs a vulnerable software version.

The device is affected if it runs a software version within the specified vulnerable ranges AND has the TWAMP server feature enabled or configured.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 17.2.3
Interim mitigation

Apply Cisco security updates when available. For IOS XR, disable debugs on the ipsla_ippm_server process as a workaround. Consider disabling the TWAMP server feature if not required.

Recommended fix Moderate confidence

Cisco IOS XE 17.3.1 or later (17.x latest stable); Cisco IOS XR 6.6.1 or later; Cisco IOS 15.x is End-of-Life - migrate to IOS XE

  1. 1. Identify the current Cisco IOS/IOS XE/IOS XR version on the device using 'show version'
  2. 2. For Cisco IOS: Upgrade to a version newer than 15.9(3)m11 (Cisco IOS 15.x is End-of-Life; consider migrating to IOS XE)
  3. 3. For Cisco IOS XE: Upgrade to version 17.3 or later (17.3.1 or latest stable 17.x release) to resolve the TWAMP server vulnerability
  4. 4. For Cisco IOS XR: Upgrade to version 6.6.1 or later to resolve the ipsla_ippm_server process vulnerability
  5. 5. After upgrade, verify the device configuration for TWAMP server feature if not needed: use 'no twamp server' in global configuration to disable if unused
  6. 6. For IOS XR: Ensure debugs are disabled in production unless actively troubleshooting, as debugs were required for the IOS XR attack vector
  7. 7. Reload the device and verify normal operation post-upgrade
Caveat Upgrading major IOS/IOS XE versions may introduce configuration changes; review Cisco release notes for new features and any deprecated commands before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in iOS Scoped from the published advisory
  • Consultation6.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
19.0 hours of engineering $3,360
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-20154 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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