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vuln-cve/data/2025/71xxx/CVE-2025-71070.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2025-71070",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-01-13T15:30:19.647Z",
"datePublished": "2026-01-13T15:31:24.709Z",
"dateUpdated": "2026-08-05T12:11:51.227Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-08-05T12:11:51.227Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nublk: clean up user copy references on ublk server exit\n\nIf a ublk server process releases a ublk char device file, any requests\ndispatched to the ublk server but not yet completed will retain a ref\nvalue of UBLK_REFCOUNT_INIT. Before commit e63d2228ef83 (\"ublk: simplify\naborting ublk request\"), __ublk_fail_req() would decrement the reference\ncount before completing the failed request. However, that commit\noptimized __ublk_fail_req() to call __ublk_complete_rq() directly\nwithout decrementing the request reference count.\nThe leaked reference count incorrectly allows user copy and zero copy\noperations on the completed ublk request. It also triggers the\nWARN_ON_ONCE(refcount_read(&io->ref)) warnings in ublk_queue_reinit()\nand ublk_deinit_queue().\nCommit c5c5eb24ed61 (\"ublk: avoid ublk_io_release() called after ublk\nchar dev is closed\") already fixed the issue for ublk devices using\nUBLK_F_SUPPORT_ZERO_COPY or UBLK_F_AUTO_BUF_REG. However, the reference\ncount leak also affects UBLK_F_USER_COPY, the other reference-counted\ndata copy mode. Fix the condition in ublk_check_and_reset_active_ref()\nto include all reference-counted data copy modes. This ensures that any\nublk requests still owned by the ublk server when it exits have their\nreference counts reset to 0."
}
],
"metrics": [
{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - Exploitation uses local close, io_uring, and pread/pwrite operations on a ublk character device; no network or physical path reaches the flaw.\nAC:L - A malicious server can control the outstanding I/O, server exit, request generation, and concurrent copy/commit operations. It can park the dispatch task or stall user copying, so the relevant race does not depend on uncontrollable conditions.\nPR:L - The data-plane open/read/write path has no capability check and explicitly supports non-CAP_SYS_ADMIN daemon tasks when device-node access is delegated. Device provisioning and recovery require initial-namespace CAP_SYS_ADMIN, but a low-privileged daemon account can exploit an already managed USER_COPY device.\nUI:N - The attacker can generate the necessary block I/O and server shutdown/recovery sequence without another user's action.\nS:U - The vulnerable ublk code and the affected kernel memory and execution context belong to the same kernel security authority.\nC:H - The stale reference can permit a copy before dispatch resets the refcount, after which concurrent completion can free or reuse bio, bvec, and request pages still being traversed. A pread operation can therefore disclose broadly controllable freed or reallocated kernel-backed memory.\nI:H - A concurrent pwrite can operate through freed or attacker-groomed bio/bvec state, providing a path to corrupt reused pages or redirect writes to kernel memory and potentially hijack control flow.\nA:H - The resulting use-after-free can cause an oops or kernel panic, and the deterministic WARN_ON_ONCE sites can also panic systems configured with panic-on-warn."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/block/ublk_drv.c"
],
"versions": [
{
"version": "e63d2228ef831af36f963b3ab8604160cfff84c1",
"lessThan": "13456b4f1033d911f8bf3a0a1195656f293ba0f6",
"status": "affected",
"versionType": "git"
},
{
"version": "e63d2228ef831af36f963b3ab8604160cfff84c1",
"lessThan": "daa24603d9f0808929514ee62ced30052ca7221c",
"status": "affected",
"versionType": "git"
},
{
"version": "e537193fc4a43b48ac51cc6366319e15e32dd540",
"status": "affected",
"versionType": "git"
},
{
"version": "6.14.6",
"lessThan": "6.15",
"status": "affected",
"versionType": "semver"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/block/ublk_drv.c"
],
"versions": [
{
"version": "6.15",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.15",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.18.3",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.19",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.15",
"versionEndExcluding": "6.18.3"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.15",
"versionEndExcluding": "6.19"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.14.6"
}
]
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/13456b4f1033d911f8bf3a0a1195656f293ba0f6"
},
{
"url": "https://git.kernel.org/stable/c/daa24603d9f0808929514ee62ced30052ca7221c"
}
],
"title": "ublk: clean up user copy references on ublk server exit",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
}
}