{"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"}}}}