Executive brief
Arista EOS networking equipment running OSPFv2 (a core routing protocol) with cryptographic authentication configured is vulnerable to a specially crafted packet attack from an adjacent network segment. An attacker can craft malicious packets that cause routing adjacencies to repeatedly flap and drop packets, disrupting traffic routing across the network infrastructure and potentially affecting service availability.
Technical details
The vulnerability is a failure to properly verify the authenticity of OSPFv2 protocol data units (PDUs), classified as CWE-345. An unauthenticated attacker on the same broadcast network segment can send specially crafted OSPFv2 packets that bypass or circumvent the configured cryptographic authentication (MD5 or SHA-based), triggering repeated adjacency state flapping and packet loss. The attack requires that OSPFv2 authentication be configured on a broadcast interface with at least two neighbors. The vulnerability affects Arista EOS versions 4.36.1F and below across multiple product lines (7050/7060/7150/7250/7260/7280/7300/7320/7500/7800 series and others). A patch is available in newer EOS releases.
Affected products
- Arista EOS 4.36.1F and below
Timeline
- 2026-09-09: disclosed: Security Advisory 0171 initial release
- 2026-09-16: advisory: CVE-2026-73435 published
- 2026-09-22: other: CSAF JSON file added to advisory