This issue was reported externally by Dravanet Inc., and Arista is not aware of any malicious exploitation of this vulnerability in customer networks.
Analysis and contextual insights are available on OpenCVE Cloud.
Vendor Solution
The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below. CVE-2026-73438 has been fixed in the following releases: - 4.36.2F and later releases in the 4.36.x train - 4.35.6M and later releases in the 4.35.x train - 4.34.8M and later releases in the 4.34.x train - 4.33.10M and later releases in the 4.33.x train No hotfix is available for this issue.
Vendor Workaround
The OSPFv3 authentication feature helps to mitigate this vulnerability. OSPFv3 authentication prevents unauthorized actors from injecting crafted packets into the OSPF domain. Enabling it on all OSPFv3-speaking interfaces ensures that packets from unauthenticated senders are discarded before they can trigger this vulnerability. Per-interface OSPFv3 encryption: Configure ESP-based encryption with authentication on each OSPFv3 interface. All peers on the same interface must use the same SPI, algorithm, and passphrase. switch(config)# interface <interface-name> switch(config-if)# ospfv3 encryption ipsec spi <spi-value> esp aes-256-cbc sha1 passphrase <shared-passphrase> Per-area OSPFv3 configuration: Configure ESP-based encryption with authentication on each OSPFv3 area. switch(config)# router ospfv3 switch(config-router-ospfv3)# address-family ipv4 switch(config-router-ospfv3-af)# area <area-id> encryption ipsec spi <spi-value> esp aes-256-cbc sha1 passphrase <shared-passphrase> switch(config-router-ospfv3-af)# address-family ipv6 switch(config-router-ospfv3-af)# area <area-id> encryption ipsec spi <spi-value> esp aes-256-cbc sha1 passphrase <shared-passphrase> Caution: Enabling OSPFv3 authentication must be coordinated across peering neighbors simultaneously. Applying this configuration to a single peer will temporarily break the routing adjacency, resulting in traffic disruption.
Tracking
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Wed, 16 Sep 2026 19:30:00 +0000
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Wed, 16 Sep 2026 10:00:00 +0000
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| Description | On affected platforms running Arista EOS with Open Shortest Path First version 3 (OSPFv3) configured, an unauthenticated attacker on the same OSPFv3 broadcast domain can send a specially crafted set of packets that can cause the Ospf3 agent to restart unexpectedly. The crash results in the loss of all OSPFv3 adjacencies on the affected device and may disrupt routing across the broader OSPF domain until the agent recovers. This issue was reported externally by Dravanet Inc., and Arista is not aware of any malicious exploitation of this vulnerability in customer networks. | |
| Title | Security Advisory 0172 | |
| Weaknesses | CWE-617 | |
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| Metrics |
cvssV3_1
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Subscriptions
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Status: PUBLISHED
Assigner: Arista
Published:
Updated: 2026-09-16T18:03:38.266Z
Reserved: 2026-08-12T16:39:35.977Z
Link: CVE-2026-73438
Updated: 2026-09-16T18:03:18.420Z
Status : Awaiting Analysis
Published: 2026-09-16T10:16:51.690
Modified: 2026-09-16T19:17:30.513
Link: CVE-2026-73438
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OpenCVE Enrichment
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