Executive brief
Alibaba XQUIC is a high-performance implementation of the QUIC network protocol used for fast and secure data transfer. A vulnerability in how it handles initial connection requests allows an attacker to manipulate protocol states by sending malformed data packets. This could lead to unauthorized modification of connection parameters or bypass of certain security checks during the handshake process.
Technical details
A vulnerability exists in XQUIC's packet processing module, specifically within the STREAM frame handler. The implementation fails to properly validate the presence of STREAM frames in Initial (INIT) and Handshake (HSK) packets, which are prohibited by the QUIC specification. An unauthenticated remote attacker can exploit this by sending malformed packets to trigger improper protocol states or bypass cryptographic signature verification steps. The fix involves explicitly checking the packet type in `xqc_process_stream_frame` and closing connections that include illegal STREAM frames with a PROTOCOL_VIOLATION error.
Affected products
- Alibaba xquic through 1.8.3
Timeline
- 2026-04-15: advisory: CVE published by Alibaba, Inc.
- 2026-04-15: patched: Fix committed to GitHub repository