Linux Kernel io_uring zcrx: Buffer Offset Off-by-4GB
CVE-2026-99266 Published on November 3, 2026
io_uring/zcrx: fix buffer offsets in areas above 4GB
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.
Products Associated with CVE-2026-99266
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Affected Versions
Linux:- Version 11ed914bbf948c4a37248f2876973ac18014056d and below 9bfb315e2d0907fbcaf5d0453dd6d873c9aa8d5b is affected.
- Version 11ed914bbf948c4a37248f2876973ac18014056d and below 51f4ee29bf0564e6ae7d3540693a9bc1dd2c8fd7 is affected.
- Version 6.15 is affected.
- Before 6.15 is unaffected.
- Version 6.18.60, <= 6.18.* is unaffected.
- Version 7.2.14, <= 7.2.* is unaffected.