The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

A packet of death scenario is possible in mvfst via a specially crafted message during a QUIC session, which causes a crash via a failed assertion. Per QUIC specification, this particular message should be treated as a connection error. This issue affects mvfst versions prior to commit a67083ff4b8dcbb7ee2839da6338032030d712b0 and proxygen versions prior to v2021.03.15.00.

A use-after-free is possible due to an error in lifetime management in the request adaptor when a malicious client invokes request error handling in a specific sequence. This issue affects versions of proxygen prior to v2020.05.18.00.

In the course of decompressing HPACK inside the HTTP2 protocol, an unexpected sequence of header table resize operations can place the header table into a corrupted state, leading to a use-after-free condition and undefined behavior. This issue affects Proxygen from v0.29.0 until v2017.04.03.00.

An out of bounds write is possible via a specially crafted packet in certain configurations of Proxygen due to improper handling of Base64 when parsing malformed binary content in Structured HTTP Headers. This issue affects versions of proxygen prior to v2019.07.22.00.

A potential denial-of-service issue in the Proxygen handling of invalid HTTP2 priority settings (specifically a circular dependency). This affects Proxygen prior to v2018.12.31.00.

An issue in the Proxygen handling of HTTP2 parsing of headers/trailers can lead to a denial-of-service attack. This affects Proxygen prior to v2018.12.31.00.

Proxygen fails to validate that a secondary auth manager is set before dereferencing it. That can cause a denial of service issue when parsing a Certificate/CertificateRequest HTTP2 Frame over a fizz (TLS 1.3) transport. This issue affects Proxygen releases starting from v2018.10.29.00 until the fix in v2018.11.19.00.

The SPDY/2 codec in Facebook Proxygen before 2015-11-09 truncates a certain field to two bytes, which allows hijacking and injection attacks.

Facebook Proxygen before 2015-11-09 mismanages HTTPMessage.request state, which allows remote attackers to conduct hijacking attacks and bypass ACL checks.