dbcve.org
Ios XrOperating system · Cisco

CVE-2025-20115

HIGH · 8.6 CVSS v3.1 Published 2025-03-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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 confederation implementation for the Border Gateway Protocol (BGP) in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. This vulnerability is due to a memory corruption that occurs when a BGP update is created with an AS_CONFED_SEQUENCE attribute that has 255 autonomous system numbers (AS numbers). An attacker could exploit this vulnerability by sending a crafted BGP update message, or the network could be designed in such a manner that the AS_CONFED_SEQUENCE attribute grows to 255 AS numbers or more. A successful exploit could allow the attacker to cause memory corruption, which may cause the BGP process to restart, resulting in a DoS condition. To exploit this vulnerability, an attacker must control a BGP confederation speaker within the same autonomous system as the victim, or the network must be designed in such a manner that the AS_CONFED_SEQUENCE attribute grows to 255 AS numbers or more.

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

Memory corruption vulnerability in Cisco IOS XR BGP confederation implementation triggered by malformed BGP updates containing AS_CONFED_SEQUENCE attributes with 255 AS numbers, causing BGP process restart and DoS.

MitigationApply Cisco IOS XR security updates when available; limit AS_CONFED_SEQUENCE attribute size through network design or filtering; restrict BGP confederation peer access to trusted speakers.

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
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 Cisco IOS XR version
    Run 'show version' or 'admin show version' on the device and note the IOS XR release number (e.g., 6.5.x)
    Affected if The version matches any of these: 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
  2. Verify BGP is enabled
    Run 'show bgp process' or check configuration with 'show running-config router bgp' to confirm BGP process is active
    Affected if BGP process is running on the device
  3. Confirm BGP confederation is configured
    Run 'show running-config router bgp' and look for 'bgp confederation' commands, or use 'show bgp confederation'
    Affected if BGP confederation is configured (the vulnerability only triggers in confederation-enabled BGP setups)

The device is vulnerable if it runs an affected IOS XR version (6.5.x listed above), has BGP enabled, and has BGP confederation configured, as the flaw exploits the confederation handling of AS_CONFED_SEQUENCE attributes with exactly 255 AS numbers.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Cisco IOS XR security updates when available; limit AS_CONFED_SEQUENCE attribute size through network design or filtering; restrict BGP confederation peer access to trusted speakers.

Recommended fix Moderate confidence

Cisco IOS XR 6.5.4 or later in the 6.5.x train (6.5.15, 6.5.16, or latest 6.5.x stable release)

  1. 1. Identify the current Cisco IOS XR version using 'show version' command
  2. 2. Download the fixed IOS XR release (6.5.4 or later, or the latest 6.5.x release) from Cisco.com software download center
  3. 3. Verify the fix is included in the release by reviewing the Cisco Security Advisory for CVE-2025-20115
  4. 4. Schedule a maintenance window as BGP process restart will cause network disruption
  5. 5. Back up the current configuration using 'admin commit replace' or 'export configuration'
  6. 6. Install the new IOS XR image following standard Cisco upgrade procedures
  7. 7. After reboot, verify the BGP process is stable with 'show bgp process' and 'show bgp summary'
  8. 8. Confirm the IOS XR version matches the expected fixed release with 'show version'
Caveat Standard IOS XR upgrade - requires reload which causes BGP session disruption; verify hardware compatibility before upgrading

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

Fix this in Ios Xr Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2025-20115 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data