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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 15 Apr 2022.
Ios XrOperating system · Cisco

CVE-2010-3035

HIGH · 7.5 CVSS v3.1 Published 2010-08-30
Fix available
A fix is available. Upgrade to after 3.9.1 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild 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
Cisco IOS XR 3.4.0 through 3.9.1, when BGP is enabled, does not properly handle unrecognized transitive attributes, which allows remote attackers to cause a denial of service (peering reset) via a crafted prefix announcement, as demonstrated in the wild in August 2010 with attribute type code 99, aka Bug ID CSCti62211.

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

Cisco IOS XR versions 3.4.0 through 3.9.1 fail to properly handle unrecognized transitive BGP attributes. When a remote attacker sends a crafted BGP prefix announcement containing an unrecognized transitive attribute (such as type code 99), the IOS XR device triggers a BGP peering reset, causing denial of service.

MitigationUpgrade Cisco IOS XR to a version beyond 3.9.1 that includes the fix for this vulnerability. As a temporary mitigation, implement BGP route filtering at network edges to drop updates with unrecognized transitive attributes.

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:>= 3.4.0, <= 3.9.1

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
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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
    Execute 'show version' or 'show install active' in the IOS XR CLI to display the running software version
    Affected if Version is 3.4.0, 3.4.1, 3.4.2, 3.4.3, 3.4.4, 3.4.5, 3.4.6, 3.4.7, 3.4.8, 3.4.9, 3.5.0, 3.5.1, 3.5.2, 3.5.3, 3.5.4, 3.6.0, 3.6.1, 3.6.2, 3.7.0, 3.7.1, 3.7.2, 3.7.3, 3.8.0, 3.8.1, 3.8.2, 3.9.0, or 3.9.1
  2. Confirm BGP is configured
    Execute 'show bgp summary' or 'show bgp vrf all summary' to verify BGP is running and has configured neighbors
    Affected if BGP process is active with one or more configured neighbors
  3. Examine BGP peer trust relationships
    Execute 'show bgp neighbors' to list all configured BGP peers and their configuration, then review whether any peers are from untrusted external networks
    Affected if The device has BGP peers that are not explicitly filtered or trusted, particularly external BGP (eBGP) peers from untrusted networks

The device is vulnerable if it runs Cisco IOS XR version 3.4.0 through 3.9.1, has BGP enabled, and maintains BGP peer relationships with untrusted external networks that could send crafted BGP updates with unrecognized transitive attributes.

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 3.9.1
Interim mitigation

Upgrade Cisco IOS XR to a version beyond 3.9.1 that includes the fix for this vulnerability. As a temporary mitigation, implement BGP route filtering at network edges to drop updates with unrecognized transitive attributes.

Recommended fix Moderate confidence

Any IOS XR version after 3.9.1 (e.g., 4.0.0 or later stable release)

  1. 1. Contact Cisco TAC or visit the Cisco Security Advisories page to obtain the specific fixed release for CSCti62211
  2. 2. Schedule a maintenance window for the IOS XR device upgrade
  3. 3. Before upgrading, backup the current IOS XR configuration using 'admin commit' and 'show running-config'
  4. 4. Download the fixed IOS XR release from Cisco (versions after 3.9.1 contain the fix)
  5. 5. Upgrade the IOS XR software following Cisco's standard upgrade procedures for your hardware platform
  6. 6. After reboot, verify BGP peering is stable and check 'show bgp neighbor' to confirm sessions are established
  7. 7. Monitor for any attribute type 99 (or other unrecognized transitive) BGP updates in logs
Caveat Review Cisco IOS XR release notes for migration path from 3.x to 4.x series as there may be configuration and feature changes

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

Fix this in Ios Xr Exploited in the wild — priority engagement
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  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
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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-2010-3035 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