CVE-2010-3035: Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service Vulnerability

CVE-2010-3035 is a denial-of-service vulnerability in Cisco IOS XR when Border Gateway Protocol (BGP) is configured as a routing feature. Improper input validation (CWE-20) can allow a remote attacker to disrupt BGP operation and affect routing availability on affected devices. For operators running IOS XR in production networks, this matters because BGP instability can interrupt reachability and force recovery work under pressure. Confirm exact product and configuration details against the vendor advisory.

How it works

The weakness is improper input validation in the BGP handling path of Cisco IOS XR. When BGP is enabled, crafted or unexpected protocol input that is not adequately checked can cause the routing process or related services to fail, producing a denial-of-service condition rather than a controlled rejection of bad data.

An attacker who can send BGP-related traffic to a vulnerable device may trigger that failure remotely. Public detail in the provided record does not describe packet formats, session requirements, or exploit mechanics; treat any such claims as unverified unless they appear in the vendor advisory. The practical outcome is loss of BGP stability or process availability on the affected router, which can cascade into routing disruption for networks that depend on that device.

Am I affected? How to find it in your systems

Cisco IOS XR is commonly deployed on service-provider and large-enterprise edge and core routers where BGP is used for inter-domain or large-scale internal routing. Inventory every platform running IOS XR and determine whether BGP is configured.

• Export hardware and software inventory from your NMS, configuration management database, or CLI/automation (show version, show inventory, and BGP configuration sections).
• Flag devices with BGP neighbors, address families, or routing policies enabled; the CISA summary ties the issue to BGP as the configured routing feature.
• Compare installed software trains and releases to the fixed versions listed in the Cisco advisory for CVE-2010-3035; do not assume version ranges from secondary sources.
• Review change and compliance records for any temporary BGP features, route reflectors, or peering that might have been enabled outside standard baselines.

For exploitation signs, watch BGP session resets, unexpected process restarts or core dumps on the routing stack, sudden loss of prefixes, and syslog or telemetry spikes correlated with external peering activity. These symptoms are generic to BGP DoS and process faults; confirm interpretation against vendor guidance and your baseline behavior. There is no substitute for matching your exact image and configuration to the advisory.

How to remediate

Patch first. Apply the updates Cisco specifies for CVE-2010-3035 on every affected IOS XR system, following the vendor’s install and reload procedures for your platform. CISA’s required action is to apply updates per vendor instructions; schedule maintenance windows accordingly and verify post-upgrade BGP adjacency and route tables.

• After patching, re-validate BGP configurations, authentication (where used), and maximum-prefix or dampening policies so hardened settings remain in place.
• Limit BGP exposure to required peers only; remove unused address families and stale neighbor statements.
• Enforce control-plane protection and receive ACLs so only legitimate peer addresses can reach BGP ports and processes.
• Document the fixed release in your golden image and block redeployment of vulnerable trains.

If the advisory lists workarounds or feature-specific notes, implement those only as described by Cisco; do not invent configuration knobs.

If you can't patch immediately

Reduce attack surface until you can upgrade. Segment management and control-plane access so BGP speakers are not reachable from untrusted networks. Use infrastructure ACLs, control-plane policing, and strict neighbor definitions so only known peer IPs can form sessions. Where a WAF or virtual patching appliance sits in front of management paths, it will not replace IOS XR fixes for BGP on the router itself; focus on network-layer filtering and peer restriction.

• Disable BGP on devices that do not require it; prefer static or IGP-only designs where that is operationally sound.
• Increase monitoring on BGP state, process health, and interface errors; alert on mass session drops or CPU spikes on the routing process.
• Prepare rollback and traffic-shift plans so a DoS event can be isolated by withdrawing a peer or moving traffic to a patched path.

These steps lower likelihood and impact; they are not a permanent substitute for the vendor update.

If your data may have been exposed

This record describes a denial-of-service issue and does not document ransomware use or confidentiality impact. Actively exploited vulnerabilities can still lead to broader incidents if attackers use disruption as cover or pivot after gaining another foothold. If you suspect compromise beyond BGP instability, follow your incident response process: preserve logs, isolate affected devices, and verify integrity of configurations and images. You can run a free exposure scan of your email addresses against known breach data to see whether credentials or identities appear in unrelated third-party breaches while you complete containment and patching.