CVE-2026-64535 is a vulnerability in Linux Kernel
Published on July 27, 2026
nvmet-tcp: Fix potential UAF when ddgst mismatch
In the Linux kernel, the following vulnerability has been resolved:
nvmet-tcp: Fix potential UAF when ddgst mismatch
Shivam Kumar found via vulnerability testing:
When data digest is enabled on an NVMe/TCP connection and a digest
mismatch occurs on a non-final H2C_DATA PDU during an R2T-based
data transfer, the digest error handler in nvmet_tcp_try_recv_ddgst()
calls nvmet_req_uninit() which performs percpu_ref_put() on the
submission queue but does NOT mark the command as completed. It
does not set cqe->status, does not modify rbytes_done, and does not
clear any flag. When the subsequent fatal error triggers queue
teardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands,
checks nvmet_tcp_need_data_in() for each one, and finds that the
already-uninited command still appears to need data (because
rbytes_done < transfer_len and cqe->status == 0). It therefore calls
nvmet_req_uninit() a second time on the same command a double
percpu_ref_put against a single percpu_ref_get.
Products Associated with CVE-2026-64535
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Affected Versions
Linux:- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 96fe2513df590e74b04253a45089cae75569570e is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below e091ff83d962f9ed00d9bd70443676de9fe98bdc is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 6f9442983a3e4227afd1c83a5251ddbca585ea21 is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below 088ee46c18d99baef453afd74181dd40ade044ad is affected.
- Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and below dbbd07d0a7020b80f6a7028e561908f7b83b3d5a is affected.
- Before 6.1.178 is affected.
- Before 6.6.145 is affected.
- Before 6.12.97 is affected.
- Before 6.18.40 is affected.
- Version 6.1.178, <= 6.1.* is unaffected.
- Version 6.6.145, <= 6.6.* is unaffected.
- Version 6.12.97, <= 6.12.* is unaffected.
- Version 6.18.40, <= 6.18.* is unaffected.
- Version 7.1, <= * is unaffected.