CVE-2026-73468 in EOS
Summary
by MITRE • 09/16/2026
A specially crafted packet can cause the premature expiry of multicast forwarding state on affected interfaces, potentially resulting in temporary multicast traffic loss during the affected period.
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability described involves a critical flaw in the handling of multicast routing protocols within network infrastructure devices, specifically affecting how forwarding states are maintained and expired. Multicast communication relies heavily on dynamic protocol mechanisms to establish and maintain state information regarding group memberships and upstream paths. When an attacker crafts specific packets designed to exploit parsing or logic errors in these protocols, they can trigger a premature expiration of the multicast forwarding table entries. This is not merely a minor configuration drift but a fundamental breakdown in the persistence of routing state required for efficient data delivery. The flaw likely stems from insufficient validation of packet headers or sequence numbers, allowing malformed inputs to be interpreted as valid timeout signals by the device's control plane.
From an operational perspective, this vulnerability leads directly to temporary multicast traffic loss across affected interfaces. Multicast is often used for high-bandwidth applications such as video streaming, financial market data distribution, and real-time collaboration tools where continuous connectivity is paramount. When the forwarding state expires prematurely, the network devices cease to forward packets destined for those multicast groups until new join messages are received and processed by neighboring routers or switches. This creates a window of unavailability that can disrupt services relying on low-latency, high-throughput data streams. The impact is particularly severe in environments where rapid re-convergence is not possible due to protocol limitations or network topology constraints, leading to noticeable service degradation for end-users.
This type of vulnerability aligns with CWE-20 Improper Input Validation and potentially CWE-367 Time-of-check Time-of-use (TOCTOU) race conditions if the expiration logic involves checking state validity against external triggers without proper locking mechanisms. In terms of offensive security frameworks, this behavior can be leveraged in Denial of Service attacks categorized under MITRE ATT&CK technique T1498 Network Denial of Service. An adversary could exploit this by continuously sending crafted packets to keep the multicast forwarding states in a perpetual state of expiration and re-establishment, thereby consuming CPU resources on the control plane while simultaneously disrupting traffic flow. The attack vector typically requires network access but may not require authentication if the affected interfaces are exposed or if the protocol allows unauthenticated message processing for efficiency reasons.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. Vendors should release patches that address the specific parsing logic errors allowing premature state expiration, ensuring strict validation of multicast packet structures before they influence routing tables. Network administrators can implement ingress filtering to drop malformed packets at network boundaries, reducing the attack surface exposed to potential exploitation. Additionally, configuring appropriate timeout values and heartbeat intervals for multicast protocols like PIM or IGMP can provide a buffer against accidental or malicious premature expirations. Regular monitoring of control plane CPU utilization and multicast routing table stability is essential to detect anomalies indicative of such an exploit in progress. Ultimately, keeping network infrastructure firmware up to date with the latest security advisories remains the most effective defense against this class of protocol-level vulnerabilities.