GHSA-5WFV-MPG7-6VCR
Vulnerability from github – Published: 2026-07-27 09:31 – Updated: 2026-08-19 18:32In 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.
{
"affected": [],
"aliases": [
"CVE-2026-64535"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-27T08:16:22Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnvmet-tcp: Fix potential UAF when ddgst mismatch\n\nShivam Kumar found via vulnerability testing:\nWhen data digest is enabled on an NVMe/TCP connection and a digest\nmismatch occurs on a non-final H2C_DATA PDU during an R2T-based\ndata transfer, the digest error handler in nvmet_tcp_try_recv_ddgst()\ncalls nvmet_req_uninit() \u2014 which performs percpu_ref_put() on the\nsubmission queue \u2014 but does NOT mark the command as completed. It\ndoes not set cqe-\u003estatus, does not modify rbytes_done, and does not\nclear any flag. When the subsequent fatal error triggers queue\nteardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands,\nchecks nvmet_tcp_need_data_in() for each one, and finds that the\nalready-uninited command still appears to need data (because\nrbytes_done \u003c transfer_len and cqe-\u003estatus == 0). It therefore calls\nnvmet_req_uninit() a second time on the same command \u2014 a double\npercpu_ref_put against a single percpu_ref_get.",
"id": "GHSA-5wfv-mpg7-6vcr",
"modified": "2026-08-19T18:32:01Z",
"published": "2026-07-27T09:31:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64535"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/088ee46c18d99baef453afd74181dd40ade044ad"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6f9442983a3e4227afd1c83a5251ddbca585ea21"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7e558308eba14c8136cb1e615f0c850f76d1fc0a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/96fe2513df590e74b04253a45089cae75569570e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dfb902462bca478f050224ec7a7195aafa7643b1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e091ff83d962f9ed00d9bd70443676de9fe98bdc"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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