{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40099", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.164Z", "datePublished": "2025-10-30T09:48:05.859Z", "dateUpdated": "2026-08-05T12:07:48.660Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:07:48.660Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: parse_dfs_referrals: prevent oob on malformed input\n\nMalicious SMB server can send invalid reply to FSCTL_DFS_GET_REFERRALS\n\n- reply smaller than sizeof(struct get_dfs_referral_rsp)\n- reply with number of referrals smaller than NumberOfReferrals in the\nheader\n\nProcessing of such replies will cause oob.\n\nReturn -EINVAL error on such replies to prevent oob-s." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H", "baseScore": 9.4, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable parser operates directly on a FSCTL_DFS_GET_REFERRALS reply received from a remote SMB server over TCP/445, with both the buffer length (`OutputCount`) and the referral count attacker-controlled. A malicious, compromised, or MITM'd server reaches this code purely over the network.\nAC:L - The server sends one well-formed V3 referral (so the in-bounds VersionNumber check passes) together with NumberOfReferrals=0xFFFF, and the loop deterministically walks ~2.2 MB past the allocation. No race, no heap grooming, no memory-layout dependency.\nPR:N - The attacker is the remote SMB peer and needs no credentials or account on the victim client; the client initiates the connection and parses the reply. A network MITM on an unsigned/unencrypted SMB session can inject the malformed referral response with no privileges at all.\nUI:N - On an existing DFS mount the `dfs_cache_refresh` delayed work re-issues referral requests on a timer and re-queues itself indefinitely, so a compromised or MITM'd server triggers the parse with zero user action; reconnect/failover paths do the same.\nS:U - The out-of-bounds access is confined to the kernel's own heap within the same security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - Unbounded out-of-bounds read of up to ~2.2 MB of adjacent kernel heap, far beyond a \"few bytes\"; the harvested ServerType/ReferralEntryFlags/TimeToLive values are stored into DFS cache entries and exposed to any local user through world-readable (0644) /proc/fs/cifs/dfscache.\nI:L - There is no out-of-bounds write, but uncontrolled out-of-bounds heap contents are written into `dfs_info3_param` fields and propagated into the client's cached DFS referral state (ttl, srvtype, ref_flags), a limited corruption of kernel-side data that the fix explicitly prevents.\nA:H - The linear ~2.2 MB walk past a small kmalloc object can strike an unmapped page and oops the kernel — reliably so on small-memory embedded/IoT clients, hardened allocators, and KASAN builds — and each malicious reply additionally forces a ~3 MB kcalloc, repeatable on every automatic refresh." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/misc.c" ], "versions": [ { "version": "4ecce920e13ace16a5ba45efe8909946c28fb2ad", "lessThan": "cfacc7441f760e4a73cc71b6ff1635261d534657", "status": "affected", "versionType": "git" }, { "version": "4ecce920e13ace16a5ba45efe8909946c28fb2ad", "lessThan": "15c73964da9df994302f579ed14ee5fdbce7a332", "status": "affected", "versionType": "git" }, { "version": "4ecce920e13ace16a5ba45efe8909946c28fb2ad", "lessThan": "8bc4a8d39bac23d8b044fd3e2dbfd965f1d9b058", "status": "affected", "versionType": "git" }, { "version": "4ecce920e13ace16a5ba45efe8909946c28fb2ad", "lessThan": "bb0f2e66e1ac043a5b238f5bcab4f26f3c317039", "status": "affected", "versionType": "git" }, { "version": "4ecce920e13ace16a5ba45efe8909946c28fb2ad", "lessThan": "6447b0e355562a1ff748c4a2ffb89aae7e84d2c9", "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/smb/client/misc.c" ], "versions": [ { "version": "4.11", "status": "affected" }, { "version": "0", "lessThan": "4.11", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.158", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.114", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.55", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.5", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18", "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": "4.11", "versionEndExcluding": "6.1.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "6.6.114" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "6.12.55" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "6.17.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.11", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/cfacc7441f760e4a73cc71b6ff1635261d534657" }, { "url": "https://git.kernel.org/stable/c/15c73964da9df994302f579ed14ee5fdbce7a332" }, { "url": "https://git.kernel.org/stable/c/8bc4a8d39bac23d8b044fd3e2dbfd965f1d9b058" }, { "url": "https://git.kernel.org/stable/c/bb0f2e66e1ac043a5b238f5bcab4f26f3c317039" }, { "url": "https://git.kernel.org/stable/c/6447b0e355562a1ff748c4a2ffb89aae7e84d2c9" } ], "title": "cifs: parse_dfs_referrals: prevent oob on malformed input", "x_generator": { "engine": "bippy-1.2.0" } } } }