CGA-wvxq-mvwq-53p9

Summary

quic-go's path validation mechanism can be exploited to cause denial of service

Description

An attacker can cause its peer to run out of memory sending a large number of PATH_CHALLENGE frames. The receiver is supposed to respond to each PATH_CHALLENGE frame with a PATH_RESPONSE frame. The attacker can prevent the receiver from sending out (the vast majority of) these PATH_RESPONSE frames by collapsing the peers congestion window (by selectively acknowledging received packets) and by manipulating the peer's RTT estimate.

I published a more detailed description of the attack and its mitigation in this blog post: https://seemann.io/posts/2023-12-18-exploiting-quics-path-validation/

There's no way to mitigate this attack, please update quic-go to a version that contains the fix.