{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-23364", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:46.002Z", "datePublished": "2026-03-25T10:27:46.960Z", "dateUpdated": "2026-08-05T12:21:17.856Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:21:17.856Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: Compare MACs in constant time\n\nTo prevent timing attacks, MAC comparisons need to be constant-time.\nReplace the memcmp() with the correct function, crypto_memneq()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 7.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - ksmbd is the in-kernel SMB server listening on TCP port 445, directly reachable by any network attacker.\nAC:H - This is a timing side-channel attack requiring many network requests to statistically distinguish memcmp() early-return timing differences; network jitter is beyond the attacker's control and adds noise that significantly increases exploitation difficulty.\nPR:N - The most critical vulnerable comparison (NTLMv2 MAC in ksmbd_auth_ntlmv2) is reached during the SMB session setup authentication handshake, before any credentials are verified — no prior privileges are needed.\nUI:N - The attacker directly sends SMB authentication requests to the ksmbd server; no victim user action is required.\nS:U - The vulnerability and its impact remain within the ksmbd/kernel security authority; no security boundary is crossed.\nC:H - Successful timing attack on the NTLMv2 MAC comparison enables authentication bypass, granting the attacker full read access to all SMB-shared files and data.\nI:H - Authentication bypass via forged NTLMv2 response grants write access to SMB shares, allowing arbitrary modification of shared data.\nA:N - The timing side-channel itself causes no crashes, hangs, or denial of service; it only leaks timing information about MAC correctness." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/Kconfig", "fs/smb/server/auth.c", "fs/smb/server/smb2pdu.c" ], "versions": [ { "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "8a665d733940592e671ec6afadcd0be80a091a80", "status": "affected", "versionType": "git" }, { "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "cd52a0e309659537048a864211abc3ea4c5caa63", "status": "affected", "versionType": "git" }, { "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "307afccb751f542246bd5dc68a2c1ffe1a78418c", "status": "affected", "versionType": "git" }, { "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "2cdc56ed67615ba0921383a688f24415ebe065f3", "status": "affected", "versionType": "git" }, { "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "93c0a22fec914ec4b697e464895a0f594e29fb28", "status": "affected", "versionType": "git" }, { "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "f4588b85efd6007d46b80aa1b9fb746628ffb3dc", "status": "affected", "versionType": "git" }, { "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "c5794709bc9105935dbedef8b9cf9c06f2b559fa", "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/server/Kconfig", "fs/smb/server/auth.c", "fs/smb/server/smb2pdu.c" ], "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.167", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.130", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.78", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.19", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.7", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "5.15", "versionEndExcluding": "5.15.210" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.1.167" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.130" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18.19" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.19.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8a665d733940592e671ec6afadcd0be80a091a80" }, { "url": "https://git.kernel.org/stable/c/cd52a0e309659537048a864211abc3ea4c5caa63" }, { "url": "https://git.kernel.org/stable/c/307afccb751f542246bd5dc68a2c1ffe1a78418c" }, { "url": "https://git.kernel.org/stable/c/2cdc56ed67615ba0921383a688f24415ebe065f3" }, { "url": "https://git.kernel.org/stable/c/93c0a22fec914ec4b697e464895a0f594e29fb28" }, { "url": "https://git.kernel.org/stable/c/f4588b85efd6007d46b80aa1b9fb746628ffb3dc" }, { "url": "https://git.kernel.org/stable/c/c5794709bc9105935dbedef8b9cf9c06f2b559fa" } ], "title": "ksmbd: Compare MACs in constant time", "x_generator": { "engine": "bippy-1.2.0" } } } }