{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39888", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.145Z", "datePublished": "2025-09-23T06:00:54.156Z", "dateUpdated": "2026-08-05T12:05:54.198Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:05:54.198Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfuse: Block access to folio overlimit\n\nsyz reported a slab-out-of-bounds Write in fuse_dev_do_write.\n\nWhen the number of bytes to be retrieved is truncated to the upper limit\nby fc->max_pages and there is an offset, the oob is triggered.\n\nAdd a loop termination condition to prevent overruns." } ], "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 vulnerability is reached by a local process writing a FUSE_NOTIFY_RETRIEVE message to an open /dev/fuse file descriptor; no network or physical access is involved.\nAC:L - Every parameter that determines the overflow is attacker-controlled — max_pages and max_write via the FUSE_INIT reply, file size via attribute replies, page-cache residency via FUSE_NOTIFY_STORE, and the intra-page offset via the notify message — making the overflow deterministic and repeatable.\nPR:L - An unprivileged local user suffices: FUSE is flagged FS_USERNS_MOUNT so a mount can be created inside an unprivileged user namespace (unshare -Ur), and the setuid fusermount helper offers the same on typical distros; the notify path itself has no capability check.\nUI:N - The attacker acts as both the FUSE server and the client, populating the page cache from the server side via FUSE_NOTIFY_STORE and issuing the malicious retrieve notification itself, so no victim action is needed.\nS:U - The heap corruption occurs in kernel memory belonging to the same security authority as the attacking process; this is standard kernel privilege escalation with no crossing of a hypervisor or IOMMU boundary.\nC:H - Overwriting descs[0] with a folio pointer yields a ~0xffffea00 byte offset passed to kmap_local_folio(), causing a large out-of-bounds kernel read whose contents are copied straight into the attacker's userspace read() buffer on /dev/fuse.\nI:H - This is a slab out-of-bounds write of 8 attacker-influenced bytes past the kzalloc'd allocation, and because the attacker tunes max_pages to land the allocation exactly on a kmalloc bucket boundary the write corrupts an adjacent slab object — a classic heap-corruption primitive for privilege escalation.\nA:H - The out-of-bounds write plus the resulting wild-pointer read from a bogus folio offset reliably produce memory corruption and an oops/panic, as demonstrated by the KASAN-detected slab-out-of-bounds write in the syzbot reproducer." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/fuse/dev.c" ], "versions": [ { "version": "3568a956932621cafadafc8b75fcf6dc06555105", "lessThan": "623719227b114d73a2cee45f1b343ced63ce09ec", "status": "affected", "versionType": "git" }, { "version": "3568a956932621cafadafc8b75fcf6dc06555105", "lessThan": "9d81ba6d49a7457784f0b6a71046818b86ec7e44", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/fuse/dev.c" ], "versions": [ { "version": "6.16", "status": "affected" }, { "version": "0", "lessThan": "6.16", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.8", "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": "6.16", "versionEndExcluding": "6.16.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/623719227b114d73a2cee45f1b343ced63ce09ec" }, { "url": "https://git.kernel.org/stable/c/9d81ba6d49a7457784f0b6a71046818b86ec7e44" } ], "title": "fuse: Block access to folio overlimit", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2025-39888", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-01-14T19:26:55.986332Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-787", "description": "CWE-787 Out-of-bounds Write" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-01-14T19:33:13.183Z" } } ] } }