{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31707","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-03-09T15:48:24.132Z","datePublished":"2026-05-01T13:56:05.219Z","dateUpdated":"2026-05-11T22:14:12.107Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-05-11T22:14:12.107Z"},"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":{"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"}}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/mgmt/user_config.c","fs/smb/server/transport_ipc.c"],"versions":[{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"7dd0c858e1909769a4c91842724315ee74f1a5f1","status":"affected","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"299db777ea0cfa5c407e41b045c24a14c034c27b","status":"affected","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"99c631d0366c1eab8fb188fe66425f4581ebdde4","status":"affected","versionType":"git"},{"version":"0626e6641f6b467447c81dd7678a69c66f7746cf","lessThan":"d6a6aa81eac2c9bff66dc6e191179cb69a14426b","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/mgmt/user_config.c","fs/smb/server/transport_ipc.c"],"versions":[{"version":"5.15","status":"affected"},{"version":"0","lessThan":"5.15","status":"unaffected","versionType":"semver"},{"version":"6.12.84","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.25","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.2","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1-rc1","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":"6.12.84"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.18.25"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.0.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.1-rc1"}]}]}],"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"}}}}