{"api_version":"1","generated_at":"2026-05-03T12:43:01+00:00","cve":"CVE-2026-31707","urls":{"html":"https://cve.report/CVE-2026-31707","api":"https://cve.report/api/cve/CVE-2026-31707.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31707","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31707"},"summary":{"title":"ksmbd: validate response sizes in ipc_validate_msg()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate response sizes in ipc_validate_msg()\n\nipc_validate_msg() computes the expected message size for each\nresponse type by adding (or multiplying) attacker-controlled fields\nfrom the daemon response to a fixed struct size in unsigned int\narithmetic.  Three cases can overflow:\n\n  KSMBD_EVENT_RPC_REQUEST:\n      msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;\n  KSMBD_EVENT_SHARE_CONFIG_REQUEST:\n      msg_sz = sizeof(struct ksmbd_share_config_response) +\n               resp->payload_sz;\n  KSMBD_EVENT_LOGIN_REQUEST_EXT:\n      msg_sz = sizeof(struct ksmbd_login_response_ext) +\n               resp->ngroups * sizeof(gid_t);\n\nresp->payload_sz is __u32 and resp->ngroups is __s32.  Each addition\ncan wrap in unsigned int; the multiplication by sizeof(gid_t) mixes\nsigned and size_t, so a negative ngroups is converted to SIZE_MAX\nbefore the multiply.  A wrapped value of msg_sz that happens to\nequal entry->msg_sz bypasses the size check on the next line, and\ndownstream consumers (smb2pdu.c:6742 memcpy using rpc_resp->payload_sz,\nkmemdup in ksmbd_alloc_user using resp_ext->ngroups) then trust the\nunverified length.\n\nUse check_add_overflow() on the RPC_REQUEST and SHARE_CONFIG_REQUEST\npaths to detect integer overflow without constraining functional\npayload size; userspace ksmbd-tools grows NDR responses in 4096-byte\nchunks for calls like NetShareEnumAll, so a hard transport cap is\nunworkable on the response side.  For LOGIN_REQUEST_EXT, reject\nresp->ngroups outside the signed [0, NGROUPS_MAX] range up front and\nreport the error from ipc_validate_msg() so it fires at the IPC\nboundary; with that bound the subsequent multiplication and addition\nstay well below UINT_MAX.  The now-redundant ngroups check and\npr_err in ksmbd_alloc_user() are removed.\n\nThis is the response-side analogue of aab98e2dbd64 (\"ksmbd: fix\ninteger overflows on 32 bit systems\"), which hardened the request\nside.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-05-01 14:16:20","updated_at":"2026-05-03 07:16:18"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.1","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.1","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","data":{"baseScore":7.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/299db777ea0cfa5c407e41b045c24a14c034c27b","name":"https://git.kernel.org/stable/c/299db777ea0cfa5c407e41b045c24a14c034c27b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d6a6aa81eac2c9bff66dc6e191179cb69a14426b","name":"https://git.kernel.org/stable/c/d6a6aa81eac2c9bff66dc6e191179cb69a14426b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7dd0c858e1909769a4c91842724315ee74f1a5f1","name":"https://git.kernel.org/stable/c/7dd0c858e1909769a4c91842724315ee74f1a5f1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/99c631d0366c1eab8fb188fe66425f4581ebdde4","name":"https://git.kernel.org/stable/c/99c631d0366c1eab8fb188fe66425f4581ebdde4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31707","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31707","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0626e6641f6b467447c81dd7678a69c66f7746cf 7dd0c858e1909769a4c91842724315ee74f1a5f1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0626e6641f6b467447c81dd7678a69c66f7746cf 299db777ea0cfa5c407e41b045c24a14c034c27b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0626e6641f6b467447c81dd7678a69c66f7746cf 99c631d0366c1eab8fb188fe66425f4581ebdde4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0626e6641f6b467447c81dd7678a69c66f7746cf d6a6aa81eac2c9bff66dc6e191179cb69a14426b 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 6.12.84 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.25 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.2 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":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"31707","cve":"CVE-2026-31707","epss":"0.000180000","percentile":"0.046600000","score_date":"2026-05-02","updated_at":"2026-05-03 00:00:23"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/server/mgmt/user_config.c","fs/smb/server/transport_ipc.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"7dd0c858e1909769a4c91842724315ee74f1a5f1","status":"affected","version":"0626e6641f6b467447c81dd7678a69c66f7746cf","versionType":"git"},{"lessThan":"299db777ea0cfa5c407e41b045c24a14c034c27b","status":"affected","version":"0626e6641f6b467447c81dd7678a69c66f7746cf","versionType":"git"},{"lessThan":"99c631d0366c1eab8fb188fe66425f4581ebdde4","status":"affected","version":"0626e6641f6b467447c81dd7678a69c66f7746cf","versionType":"git"},{"lessThan":"d6a6aa81eac2c9bff66dc6e191179cb69a14426b","status":"affected","version":"0626e6641f6b467447c81dd7678a69c66f7746cf","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/server/mgmt/user_config.c","fs/smb/server/transport_ipc.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":"6.12.*","status":"unaffected","version":"6.12.84","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.25","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.2","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":"6.12.84","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.25","versionStartIncluding":"5.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.2","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: validate response sizes in ipc_validate_msg()\n\nipc_validate_msg() computes the expected message size for each\nresponse type by adding (or multiplying) attacker-controlled fields\nfrom the daemon response to a fixed struct size in unsigned int\narithmetic.  Three cases can overflow:\n\n  KSMBD_EVENT_RPC_REQUEST:\n      msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;\n  KSMBD_EVENT_SHARE_CONFIG_REQUEST:\n      msg_sz = sizeof(struct ksmbd_share_config_response) +\n               resp->payload_sz;\n  KSMBD_EVENT_LOGIN_REQUEST_EXT:\n      msg_sz = sizeof(struct ksmbd_login_response_ext) +\n               resp->ngroups * sizeof(gid_t);\n\nresp->payload_sz is __u32 and resp->ngroups is __s32.  Each addition\ncan wrap in unsigned int; the multiplication by sizeof(gid_t) mixes\nsigned and size_t, so a negative ngroups is converted to SIZE_MAX\nbefore the multiply.  A wrapped value of msg_sz that happens to\nequal entry->msg_sz bypasses the size check on the next line, and\ndownstream consumers (smb2pdu.c:6742 memcpy using rpc_resp->payload_sz,\nkmemdup in ksmbd_alloc_user using resp_ext->ngroups) then trust the\nunverified length.\n\nUse check_add_overflow() on the RPC_REQUEST and SHARE_CONFIG_REQUEST\npaths to detect integer overflow without constraining functional\npayload size; userspace ksmbd-tools grows NDR responses in 4096-byte\nchunks for calls like NetShareEnumAll, so a hard transport cap is\nunworkable on the response side.  For LOGIN_REQUEST_EXT, reject\nresp->ngroups outside the signed [0, NGROUPS_MAX] range up front and\nreport the error from ipc_validate_msg() so it fires at the IPC\nboundary; with that bound the subsequent multiplication and addition\nstay well below UINT_MAX.  The now-redundant ngroups check and\npr_err in ksmbd_alloc_user() are removed.\n\nThis is the response-side analogue of aab98e2dbd64 (\"ksmbd: fix\ninteger overflows on 32 bit systems\"), which hardened the request\nside."}],"metrics":[{"cvssV3_1":{"baseScore":7.1,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-05-03T05:45:30.821Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/7dd0c858e1909769a4c91842724315ee74f1a5f1"},{"url":"https://git.kernel.org/stable/c/299db777ea0cfa5c407e41b045c24a14c034c27b"},{"url":"https://git.kernel.org/stable/c/99c631d0366c1eab8fb188fe66425f4581ebdde4"},{"url":"https://git.kernel.org/stable/c/d6a6aa81eac2c9bff66dc6e191179cb69a14426b"}],"title":"ksmbd: validate response sizes in ipc_validate_msg()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31707","datePublished":"2026-05-01T13:56:05.219Z","dateReserved":"2026-03-09T15:48:24.132Z","dateUpdated":"2026-05-03T05:45:30.821Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-05-01 14:16:20","lastModifiedDate":"2026-05-03 07:16:18","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.2}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31707","Ordinal":"1","Title":"ksmbd: validate response sizes in ipc_validate_msg()","CVE":"CVE-2026-31707","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31707","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate response sizes in ipc_validate_msg()\n\nipc_validate_msg() computes the expected message size for each\nresponse type by adding (or multiplying) attacker-controlled fields\nfrom the daemon response to a fixed struct size in unsigned int\narithmetic.  Three cases can overflow:\n\n  KSMBD_EVENT_RPC_REQUEST:\n      msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;\n  KSMBD_EVENT_SHARE_CONFIG_REQUEST:\n      msg_sz = sizeof(struct ksmbd_share_config_response) +\n               resp->payload_sz;\n  KSMBD_EVENT_LOGIN_REQUEST_EXT:\n      msg_sz = sizeof(struct ksmbd_login_response_ext) +\n               resp->ngroups * sizeof(gid_t);\n\nresp->payload_sz is __u32 and resp->ngroups is __s32.  Each addition\ncan wrap in unsigned int; the multiplication by sizeof(gid_t) mixes\nsigned and size_t, so a negative ngroups is converted to SIZE_MAX\nbefore the multiply.  A wrapped value of msg_sz that happens to\nequal entry->msg_sz bypasses the size check on the next line, and\ndownstream consumers (smb2pdu.c:6742 memcpy using rpc_resp->payload_sz,\nkmemdup in ksmbd_alloc_user using resp_ext->ngroups) then trust the\nunverified length.\n\nUse check_add_overflow() on the RPC_REQUEST and SHARE_CONFIG_REQUEST\npaths to detect integer overflow without constraining functional\npayload size; userspace ksmbd-tools grows NDR responses in 4096-byte\nchunks for calls like NetShareEnumAll, so a hard transport cap is\nunworkable on the response side.  For LOGIN_REQUEST_EXT, reject\nresp->ngroups outside the signed [0, NGROUPS_MAX] range up front and\nreport the error from ipc_validate_msg() so it fires at the IPC\nboundary; with that bound the subsequent multiplication and addition\nstay well below UINT_MAX.  The now-redundant ngroups check and\npr_err in ksmbd_alloc_user() are removed.\n\nThis is the response-side analogue of aab98e2dbd64 (\"ksmbd: fix\ninteger overflows on 32 bit systems\"), which hardened the request\nside.","Type":"Description","Title":"ksmbd: validate response sizes in ipc_validate_msg()"}]}}}