{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-52959", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-06-09T07:44:35.373Z", "datePublished": "2026-06-24T16:28:40.391Z", "dateUpdated": "2026-08-05T12:32:09.604Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:32:09.604Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirt: sev-guest: Do not use host-controlled page order in cleanup path\n\nWhen issuing an extended guest request (SVM_VMGEXIT_EXT_GUEST_REQUEST),\nget_ext_report() allocates a buffer to retrieve a certificate blob from the\nhost, keeping track of its size in report_req->certs_len.\n\nHowever, the host may return SNP_GUEST_VMM_ERR_INVALID_LEN, indicating\nan invalid buffer size, as well as the expected length of such buffer.\nget_ext_report() subsequently updates report_req->certs_len with the\nhost-controlled value, and cleans up the buffer by computing a page order\nfrom such value. This is incorrect, as the host-provided length may not\nmatch the page order of the original allocation, potentially resulting\nin corruption in the page allocator.\n\nFix this by using alloc_pages_exact() instead, and reusing @npages to\ncompute the size passed to free_pages_exact(). For consistency, also\nuse @npages to compute the size when allocating the pages, even though\nthis last change has no functional effect." } ], "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 vulnerable path is reached through local guest interfaces, primarily the /dev/sev-guest SNP_GET_EXT_REPORT ioctl and the TSM configfs report path. It is not directly reachable by network packets, adjacent protocols, or physical device insertion.\nAC:L - There is no race or fragile timing requirement; the caller can request an undersized certificate buffer and the VMM can deterministically return INVALID_LEN with a mismatched npages value. The resulting wrong-order free occurs synchronously in cleanup.\nPR:L - The driver performs no capable() or namespace privilege check before dispatching SNP_GET_EXT_REPORT; exploitation only requires access to the local attestation interface. Because device-node policy may grant non-root attestation access, the higher-severity low-privilege value is appropriate.\nUI:N - No victim human action is required once a local process or attestation agent issues the request. The corrupted cleanup path is triggered automatically by the VMM response.\nS:U - The corrupted memory is guest kernel page-allocator state governed by the vulnerable guest kernel itself. This is best modeled as kernel memory corruption within the same security authority, not a guest-to-host escape.\nC:H - The wrong-order __free_pages() can return unrelated in-use pages to the allocator, creating page aliasing and plausible arbitrary kernel memory disclosure. Under the required overestimate rule, allocator corruption is treated as high confidentiality impact.\nI:H - Freeing more pages than were allocated can let later allocations overlap live kernel objects, providing a plausible write/control-flow corruption primitive. This supports high integrity impact rather than treating the bug as a mere cleanup error.\nA:H - Page allocator corruption can immediately trigger warnings, bad-page detection, oopses, or later kernel crashes. A repeatable local request can therefore cause high availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/virt/coco/sev-guest/sev-guest.c" ], "versions": [ { "version": "3e385c0d6ce88ac9916dcf84267bd5855d830748", "lessThan": "3f6fb0211b39aaa1b841260681dd02ca6b693ed5", "status": "affected", "versionType": "git" }, { "version": "3e385c0d6ce88ac9916dcf84267bd5855d830748", "lessThan": "9e48b4f813d2c3db75d522aa82ab705ce04b7e2d", "status": "affected", "versionType": "git" }, { "version": "3e385c0d6ce88ac9916dcf84267bd5855d830748", "lessThan": "23e6a1ca04ae44806439a5a446e62e4d42e80bb4", "status": "affected", "versionType": "git" }, { "version": "0b16521f95c875e79d657cb8d6911c15080dbb80", "status": "affected", "versionType": "git" }, { "version": "6.13.8", "lessThan": "6.14", "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/virt/coco/sev-guest/sev-guest.c" ], "versions": [ { "version": "6.14", "status": "affected" }, { "version": "0", "lessThan": "6.14", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.33", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.10", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "6.14", "versionEndExcluding": "6.18.33" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.0.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14", "versionEndExcluding": "7.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13.8" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3f6fb0211b39aaa1b841260681dd02ca6b693ed5" }, { "url": "https://git.kernel.org/stable/c/9e48b4f813d2c3db75d522aa82ab705ce04b7e2d" }, { "url": "https://git.kernel.org/stable/c/23e6a1ca04ae44806439a5a446e62e4d42e80bb4" } ], "title": "virt: sev-guest: Do not use host-controlled page order in cleanup path", "x_generator": { "engine": "bippy-1.2.0" } } } }