CVE-2026-64535 (GCVE-0-2026-64535)
Vulnerability from cvelistv5
Published
2026-07-27 06:32
Modified
2026-08-19 16:28
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 91edfca6f8b364d60cde3ddefaf7d03ddf35774b Version: fda871c0ba5d2eed2cd1c881573168129da70058 Version: fda871c0ba5d2eed2cd1c881573168129da70058 Version: fda871c0ba5d2eed2cd1c881573168129da70058 Version: fda871c0ba5d2eed2cd1c881573168129da70058 Version: fda871c0ba5d2eed2cd1c881573168129da70058 Version: fda871c0ba5d2eed2cd1c881573168129da70058 Version: 4b17476d809273617d3317fa0d4ae78aa488d760 Version: 5.10.20 ≤ Version: 5.11.3 ≤ |
||
{
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"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The vulnerable NVMe/TCP target receive worker processes attacker-controlled H2C_DATA PDUs received through a listening TCP socket, making it remotely network reachable.\nAC:L - The attacker controls digest negotiation, PDU chunking, transfer length, and digest contents, allowing a non-final digest mismatch to be triggered deterministically while keeping other I/O outstanding.\nPR:N - A reasonable non-TLS target deployment using allow_any_host requires no credentials or local capabilities; the remote peer can negotiate data digests and submit the malicious protocol sequence directly.\nUI:N - Exploitation requires only network protocol traffic and no action by a victim user.\nS:U - The vulnerable receive processing and resulting kernel compromise occur within the target host\u0027s existing kernel security authority.\nC:H - The premature reference release can free queue, request, response-buffer, and percpu-ref state while asynchronous completions still access it, creating a kernel UAF capable of arbitrary memory disclosure.\nI:H - The kernel UAF exposes writes through reclaimed request and queue structures and is plausibly exploitable for arbitrary kernel memory modification or code execution.\nA:H - The refcount corruption can cause a permanent workqueue teardown deadlock, while the resulting UAF can also produce an oops or kernel panic; the network trigger can be repeated."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:28:23.449Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/dfb902462bca478f050224ec7a7195aafa7643b1"
},
{
"url": "https://git.kernel.org/stable/c/7e558308eba14c8136cb1e615f0c850f76d1fc0a"
},
{
"url": "https://git.kernel.org/stable/c/96fe2513df590e74b04253a45089cae75569570e"
},
{
"url": "https://git.kernel.org/stable/c/e091ff83d962f9ed00d9bd70443676de9fe98bdc"
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{
"url": "https://git.kernel.org/stable/c/6f9442983a3e4227afd1c83a5251ddbca585ea21"
},
{
"url": "https://git.kernel.org/stable/c/088ee46c18d99baef453afd74181dd40ade044ad"
},
{
"url": "https://git.kernel.org/stable/c/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a"
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],
"title": "nvmet-tcp: Fix potential UAF when ddgst mismatch",
"x_generator": {
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"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-64535",
"datePublished": "2026-07-27T06:32:34.859Z",
"dateReserved": "2026-07-19T15:36:31.795Z",
"dateUpdated": "2026-08-19T16:28:23.449Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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