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vuln-cve/data/2025/39xxx/CVE-2025-39815.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2025-39815",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2025-04-16T07:20:57.138Z",
"datePublished": "2025-09-16T13:00:16.250Z",
"dateUpdated": "2026-08-05T12:05:22.677Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-08-05T12:05:22.677Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRISC-V: KVM: fix stack overrun when loading vlenb\n\nThe userspace load can put up to 2048 bits into an xlen bit stack\nbuffer. We want only xlen bits, so check the size beforehand."
}
],
"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 - The bug is reached only through the KVM_SET_ONE_REG ioctl on a vCPU file descriptor obtained from /dev/kvm, requiring local access to the host. There is no remote or adjacent-network path to kvm_riscv_vcpu_set_reg_vector().\nAC:L - A single deterministic ioctl with a crafted reg->id size field (bits 52-55) triggers the overrun every time, with the attacker choosing both the copy length and the overflowing data. No race, no memory-layout guessing, and no condition outside the attacker's control on an affected RISC-V host with the V extension.\nPR:L - No capable()/CAP_SYS_ADMIN check exists anywhere on the path — only opening /dev/kvm and creating a VM/vCPU, which unprivileged users in the kvm group and sandboxed VMM processes (QEMU, crosvm) routinely have. The confined VMM process itself is the natural attacker here.\nUI:N - The attacking process performs the ioctl entirely on its own; no victim action, mount, or file open is needed.\nS:U - The attacker is host userspace and the corrupted memory is the host kernel stack of its own task — the same security authority, i.e. standard kernel privilege escalation rather than a guest-to-host or IOMMU boundary crossing.\nC:H - The attacker-controlled stack smash overwrites saved registers, frame pointers and return addresses, which is a classic route to control-flow hijack and hence arbitrary kernel memory disclosure. Per kernel scoring guidance, memory corruption leverageable for info disclosure is High.\nI:H - This is an out-of-bounds kernel stack write of up to ~32 KB with fully attacker-chosen contents and length, directly overwriting return addresses and adjacent frames — an arbitrary-write/code-execution primitive.\nA:H - Even without exploitation, overrunning the 16 KB RISC-V kernel stack reliably corrupts the stack canary, return addresses, or the VMAP guard page, producing an immediate kernel panic that any user with /dev/kvm access can trigger at will."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"arch/riscv/kvm/vcpu_vector.c"
],
"versions": [
{
"version": "2fa290372dfe7dd248b1c16f943f273a3e674f22",
"lessThan": "c76bf8359188a11f8fd790e5bbd6077894a245cc",
"status": "affected",
"versionType": "git"
},
{
"version": "2fa290372dfe7dd248b1c16f943f273a3e674f22",
"lessThan": "6d28659b692a0212f360f8bd8a58712b339f9aac",
"status": "affected",
"versionType": "git"
},
{
"version": "2fa290372dfe7dd248b1c16f943f273a3e674f22",
"lessThan": "799766208f09f95677a9ab111b93872d414fbad7",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"arch/riscv/kvm/vcpu_vector.c"
],
"versions": [
{
"version": "6.8",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.8",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.12.45",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.16.5",
"lessThanOrEqual": "6.16.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.17",
"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": "6.8",
"versionEndExcluding": "6.12.45"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.8",
"versionEndExcluding": "6.16.5"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.8",
"versionEndExcluding": "6.17"
}
]
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/c76bf8359188a11f8fd790e5bbd6077894a245cc"
},
{
"url": "https://git.kernel.org/stable/c/6d28659b692a0212f360f8bd8a58712b339f9aac"
},
{
"url": "https://git.kernel.org/stable/c/799766208f09f95677a9ab111b93872d414fbad7"
}
],
"title": "RISC-V: KVM: fix stack overrun when loading vlenb",
"x_generator": {
"engine": "bippy-1.2.0"
}
},
"adp": [
{
"metrics": [
{
"cvssV3_1": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 5.5,
"attackVector": "LOCAL",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
}
},
{
"other": {
"type": "ssvc",
"content": {
"id": "CVE-2025-39815",
"role": "CISA Coordinator",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2026-01-14T18:15:40.818434Z"
}
}
}
],
"problemTypes": [
{
"descriptions": [
{
"lang": "en",
"type": "CWE",
"description": "CWE-noinfo Not enough information"
}
]
}
],
"title": "CISA ADP Vulnrichment",
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP",
"dateUpdated": "2026-01-14T18:22:55.580Z"
}
}
]
}
}