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Security advisories

Vulnerability in Linux Kernel TCP implementation

August 6, 2018


On August 6, 2018, a vulnerability in the Linux kernel TCP implementation, called SegmentSmack, was publicly disclosed. This vulnerability allowed a remote attacker to cause a denial-of-service attack on a target server by simply establishing a TCP connection to the server and sending specific segments over the connection. Fastly has worked with the security community in advance of this disclosure to address this vulnerability in our edge networks. They pose no threat to Fastly customers.


Fastly has deployed kernel- and application-level mitigations to our entire edge network, rendering ineffective all known attacks that exploit this vulnerability.

Fix / Workarounds

Customers do not need to take any action in response to this vulnerability.

More information

You can learn more about this vulnerability here.

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