Live › vulnerability › CVE-2026-99266
In the Linux kernel's io_uring zero-copy receive path, buffer offsets are computed in 32 bits, so for areas above 4GB the completion entries point the application at the wrong memory. An application can read the wrong data and return buffers it does not own while the real buffers are never given back.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-11-03 12:20 UTC. All times on this page are UTC.
Systems running a Linux kernel with io_uring zero-copy receive (zcrx) and receive areas larger than 4GB are the exposed case, since the offset error only occurs for buffers beyond the first 4GB. The sources do not say which kernel versions are affected or whether the feature is on by default. Teams not using io_uring zcrx can likely skip it.
No product ranges from the sources yet.
Unknown from the sources.
Unknown from the sources.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
io_uring/zcrx: fix buffer offsets in areas above 4GB
io_zcrx_queue_cqe() computes the offset of the buffer in its area from net_iov_idx(), which is an unsigned int, so the shift is done in 32 bits and only the result is widened to the u64 that goes into the CQE. An area can be up to 1TB in size. For every niov beyond the first 4GB the CQE points the application at a buffer 4GB, or a multiple of that, below the one which has the data. It reads the wrong data, and then returns a buffer it doesn't own via the refill queue while the real one is never given back.
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