{"api_version":"1","generated_at":"2026-05-13T07:41:53+00:00","cve":"CVE-2026-31610","urls":{"html":"https://cve.report/CVE-2026-31610","api":"https://cve.report/api/cve/CVE-2026-31610.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31610","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31610"},"summary":{"title":"ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix mechToken leak when SPNEGO decode fails after token alloc\n\nThe kernel ASN.1 BER decoder calls action callbacks incrementally as it\nwalks the input.  When ksmbd_decode_negTokenInit() reaches the mechToken\n[2] OCTET STRING element, ksmbd_neg_token_alloc() allocates\nconn->mechToken immediately via kmemdup_nul().  If a later element in\nthe same blob is malformed, then the decoder will return nonzero after\nthe allocation is already live.  This could happen if mechListMIC [3]\noverrunse the enclosing SEQUENCE.\n\ndecode_negotiation_token() then sets conn->use_spnego = false because\nboth the negTokenInit and negTokenTarg grammars failed.  The cleanup at\nthe bottom of smb2_sess_setup() is gated on use_spnego:\n\n\tif (conn->use_spnego && conn->mechToken) {\n\t\tkfree(conn->mechToken);\n\t\tconn->mechToken = NULL;\n\t}\n\nso the kfree is skipped, causing the mechToken to never be freed.\n\nThis codepath is reachable pre-authentication, so untrusted clients can\ncause slow memory leaks on a server without even being properly\nauthenticated.\n\nFix this up by not checking check for use_spnego, as it's not required,\nso the memory will always be properly freed.  At the same time, always\nfree the memory in ksmbd_conn_free() incase some other failure path\nforgot to free it.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-04-24 15:16:40","updated_at":"2026-04-29 16:51:02"},"problem_types":["CWE-401"],"metrics":[{"version":"3.1","source":"nvd@nist.gov","type":"Primary","score":"5.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}}],"references":[{"url":"https://git.kernel.org/stable/c/ad0057fb91218914d6c98268718ceb9d59b388e1","name":"https://git.kernel.org/stable/c/ad0057fb91218914d6c98268718ceb9d59b388e1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/745a535461bbb90a56d9357573c9f97a5c12abe1","name":"https://git.kernel.org/stable/c/745a535461bbb90a56d9357573c9f97a5c12abe1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/269c800a7a7e363459291885b35f7bc72e231ed6","name":"https://git.kernel.org/stable/c/269c800a7a7e363459291885b35f7bc72e231ed6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dd577cb55588ec3fbc66af3621280306601c4192","name":"https://git.kernel.org/stable/c/dd577cb55588ec3fbc66af3621280306601c4192","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6c8c44e6553b9f072f62d9875e567766eb293162","name":"https://git.kernel.org/stable/c/6c8c44e6553b9f072f62d9875e567766eb293162","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dd53414e301beb915fe672dc4c4a51bafb917604","name":"https://git.kernel.org/stable/c/dd53414e301beb915fe672dc4c4a51bafb917604","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31610","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31610","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fad4161b5cd01a24202234976ebbb133f7adc0b5 745a535461bbb90a56d9357573c9f97a5c12abe1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fad4161b5cd01a24202234976ebbb133f7adc0b5 dd577cb55588ec3fbc66af3621280306601c4192 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fad4161b5cd01a24202234976ebbb133f7adc0b5 dd53414e301beb915fe672dc4c4a51bafb917604 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fad4161b5cd01a24202234976ebbb133f7adc0b5 269c800a7a7e363459291885b35f7bc72e231ed6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fad4161b5cd01a24202234976ebbb133f7adc0b5 6c8c44e6553b9f072f62d9875e567766eb293162 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fad4161b5cd01a24202234976ebbb133f7adc0b5 ad0057fb91218914d6c98268718ceb9d59b388e1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.136 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.83 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.24 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.14 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.1 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2026","cve_id":"31610","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"o","cpe4":"linux","cpe5":"linux_kernel","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"31610","cve":"CVE-2026-31610","epss":"0.000340000","percentile":"0.098310000","score_date":"2026-04-27","updated_at":"2026-04-28 00:06:44"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/server/connection.c","fs/smb/server/smb2pdu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"745a535461bbb90a56d9357573c9f97a5c12abe1","status":"affected","version":"fad4161b5cd01a24202234976ebbb133f7adc0b5","versionType":"git"},{"lessThan":"dd577cb55588ec3fbc66af3621280306601c4192","status":"affected","version":"fad4161b5cd01a24202234976ebbb133f7adc0b5","versionType":"git"},{"lessThan":"dd53414e301beb915fe672dc4c4a51bafb917604","status":"affected","version":"fad4161b5cd01a24202234976ebbb133f7adc0b5","versionType":"git"},{"lessThan":"269c800a7a7e363459291885b35f7bc72e231ed6","status":"affected","version":"fad4161b5cd01a24202234976ebbb133f7adc0b5","versionType":"git"},{"lessThan":"6c8c44e6553b9f072f62d9875e567766eb293162","status":"affected","version":"fad4161b5cd01a24202234976ebbb133f7adc0b5","versionType":"git"},{"lessThan":"ad0057fb91218914d6c98268718ceb9d59b388e1","status":"affected","version":"fad4161b5cd01a24202234976ebbb133f7adc0b5","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/server/connection.c","fs/smb/server/smb2pdu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.15"},{"lessThan":"5.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.136","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.83","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.24","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.14","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.1","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.136","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.83","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.24","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.14","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.1","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1-rc1","versionStartIncluding":"5.15","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix mechToken leak when SPNEGO decode fails after token alloc\n\nThe kernel ASN.1 BER decoder calls action callbacks incrementally as it\nwalks the input.  When ksmbd_decode_negTokenInit() reaches the mechToken\n[2] OCTET STRING element, ksmbd_neg_token_alloc() allocates\nconn->mechToken immediately via kmemdup_nul().  If a later element in\nthe same blob is malformed, then the decoder will return nonzero after\nthe allocation is already live.  This could happen if mechListMIC [3]\noverrunse the enclosing SEQUENCE.\n\ndecode_negotiation_token() then sets conn->use_spnego = false because\nboth the negTokenInit and negTokenTarg grammars failed.  The cleanup at\nthe bottom of smb2_sess_setup() is gated on use_spnego:\n\n\tif (conn->use_spnego && conn->mechToken) {\n\t\tkfree(conn->mechToken);\n\t\tconn->mechToken = NULL;\n\t}\n\nso the kfree is skipped, causing the mechToken to never be freed.\n\nThis codepath is reachable pre-authentication, so untrusted clients can\ncause slow memory leaks on a server without even being properly\nauthenticated.\n\nFix this up by not checking check for use_spnego, as it's not required,\nso the memory will always be properly freed.  At the same time, always\nfree the memory in ksmbd_conn_free() incase some other failure path\nforgot to free it."}],"providerMetadata":{"dateUpdated":"2026-04-27T13:56:49.304Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/745a535461bbb90a56d9357573c9f97a5c12abe1"},{"url":"https://git.kernel.org/stable/c/dd577cb55588ec3fbc66af3621280306601c4192"},{"url":"https://git.kernel.org/stable/c/dd53414e301beb915fe672dc4c4a51bafb917604"},{"url":"https://git.kernel.org/stable/c/269c800a7a7e363459291885b35f7bc72e231ed6"},{"url":"https://git.kernel.org/stable/c/6c8c44e6553b9f072f62d9875e567766eb293162"},{"url":"https://git.kernel.org/stable/c/ad0057fb91218914d6c98268718ceb9d59b388e1"}],"title":"ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31610","datePublished":"2026-04-24T14:42:31.471Z","dateReserved":"2026-03-09T15:48:24.122Z","dateUpdated":"2026-04-27T13:56:49.304Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-24 15:16:40","lastModifiedDate":"2026-04-29 16:51:02","problem_types":["CWE-401"],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.6.136","matchCriteriaId":"B1ABA9F0-A5C4-4CBE-92EC-33CA7D4F7634"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.83","matchCriteriaId":"7F0AE5B5-23AC-4DCC-B37A-51CA1DAE7BA8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.24","matchCriteriaId":"8126B8B8-6D0B-4443-86C1-672AEE893555"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"6.19.14","matchCriteriaId":"D6A8A074-BBF4-4803-ABED-519A839435BB"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0","versionEndExcluding":"7.0.1","matchCriteriaId":"9B5888AB-7403-4335-89E4-21CC0B48366A"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31610","Ordinal":"1","Title":"ksmbd: fix mechToken leak when SPNEGO decode fails after token a","CVE":"CVE-2026-31610","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31610","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix mechToken leak when SPNEGO decode fails after token alloc\n\nThe kernel ASN.1 BER decoder calls action callbacks incrementally as it\nwalks the input.  When ksmbd_decode_negTokenInit() reaches the mechToken\n[2] OCTET STRING element, ksmbd_neg_token_alloc() allocates\nconn->mechToken immediately via kmemdup_nul().  If a later element in\nthe same blob is malformed, then the decoder will return nonzero after\nthe allocation is already live.  This could happen if mechListMIC [3]\noverrunse the enclosing SEQUENCE.\n\ndecode_negotiation_token() then sets conn->use_spnego = false because\nboth the negTokenInit and negTokenTarg grammars failed.  The cleanup at\nthe bottom of smb2_sess_setup() is gated on use_spnego:\n\n\tif (conn->use_spnego && conn->mechToken) {\n\t\tkfree(conn->mechToken);\n\t\tconn->mechToken = NULL;\n\t}\n\nso the kfree is skipped, causing the mechToken to never be freed.\n\nThis codepath is reachable pre-authentication, so untrusted clients can\ncause slow memory leaks on a server without even being properly\nauthenticated.\n\nFix this up by not checking check for use_spnego, as it's not required,\nso the memory will always be properly freed.  At the same time, always\nfree the memory in ksmbd_conn_free() incase some other failure path\nforgot to free it.","Type":"Description","Title":"ksmbd: fix mechToken leak when SPNEGO decode fails after token a"}]}}}