{"id":"GHSA-fv92-fjc5-jj9h","aliases":["GO-2025-3787"],"status":"published","title":"mapstructure May Leak Sensitive Information in Logs When Processing Malformed Data","description":"### Summary\n\nUse of this library in a security-critical context may result in leaking sensitive information, if used to process sensitive fields.\n\n### Details\n\nOpenBao (and presumably HashiCorp Vault) have surfaced error messages from `mapstructure` as follows:\n\nhttps://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L43-L50\n\n```go\n\t\t\t_, _, err := d.getPrimitive(field, schema)\n\t\t\tif err != nil {\n\t\t\t\treturn fmt.Errorf(\"error converting input for field %q: %w\", field, err)\n\t\t\t}\n```\n\nwhere this calls `mapstructure.WeakDecode(...)`: https://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L181-L193\n\n```go\n\nfunc (d *FieldData) getPrimitive(k string, schema *FieldSchema) (interface{}, bool, error) {\n\traw, ok := d.Raw[k]\n\tif !ok {\n\t\treturn nil, false, nil\n\t}\n\n\tswitch t := schema.Type; t {\n\tcase TypeBool:\n\t\tvar result bool\n\t\tif err := mapstructure.WeakDecode(raw, \u0026result); err != nil {\n\t\t\treturn nil, false, err\n\t\t}\n\t\treturn result, true, nil\n```\n\nNotably, `WeakDecode(...)` eventually calls one of the decode helpers, which surfaces the original value:\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L679-L686\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L726-L730\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L783-L787\n\n\u0026 more.\n\n### PoC\n\nTo reproduce with OpenBao:\n\n```\n$ podman run -p 8300:8300 openbao/openbao:latest server -dev -dev-root-token-id=root -dev-listen-address=0.0.0.0:8300\n```\n\nand in a new tab:\n\n```\n$ BAO_TOKEN=root BAO_ADDR=http://localhost:8300 bao auth enable userpass\nSuccess! Enabled userpass auth method at: userpass/\n$ curl -X PUT -H \"X-Vault-Request: true\" -H \"X-Vault-Token: root\" -d '{\"password\":{\"asdf\":\"my-sensitive-value\"}}' \"http://localhost:8300/v1/auth/userpass/users/adsf\"\n{\"errors\":[\"error converting input for field \\\"password\\\": '' expected type 'string', got unconvertible type 'map[string]interface {}', value: 'map[asdf:my-sensitive-value]'\"]}\n```\n\n### Impact\n\nThis is an information disclosure bug with little mitigation. See https://discuss.hashicorp.com/t/hcsec-2025-09-vault-may-expose-sensitive-information-in-error-logs-when-processing-malformed-data-with-the-kv-v2-plugin/74717 for a previous version. That version was fixed, but this is in the second part of that error message (starting at `'' expected a map, got 'string'` -- when the field type is `string` and a `map` is provided, we see the above information leak -- the previous example had a `map` type field with a `string` value provided).\n\nThis was rated 4.5 Medium by HashiCorp in the past iteration.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium","from":"ghsa"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-532"],"published":"2025-06-27T16:24:59Z","modified":"2026-09-10T03:50:25Z","fixes":[{"ecosystem":"Go","package":"github.com/go-viper/mapstructure/v2","fixed_in":["2.3.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/go-viper/mapstructure/v2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/go-viper/mapstructure/v2","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.3.0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/go-viper/mapstructure","ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/go-viper/mapstructure/v2","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.3.0"}]}]}],"references":[{"url":"https://github.com/go-viper/mapstructure/security/advisories/GHSA-fv92-fjc5-jj9h","tags":["web","advisory"]},{"url":"https://github.com/advisories/GHSA-fv92-fjc5-jj9h"},{"url":"https://github.com/go-viper/mapstructure","tags":["package"]}],"sources":{"ghsa":[{"id":"GHSA-fv92-fjc5-jj9h","title":"mapstructure May Leak Sensitive Information in Logs When Processing Malformed Data","description":"### Summary\n\nUse of this library in a security-critical context may result in leaking sensitive information, if used to process sensitive fields.\n\n### Details\n\nOpenBao (and presumably HashiCorp Vault) have surfaced error messages from `mapstructure` as follows:\n\nhttps://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L43-L50\n\n```go\n\t\t\t_, _, err := d.getPrimitive(field, schema)\n\t\t\tif err != nil {\n\t\t\t\treturn fmt.Errorf(\"error converting input for field %q: %w\", field, err)\n\t\t\t}\n```\n\nwhere this calls `mapstructure.WeakDecode(...)`: https://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L181-L193\n\n```go\n\nfunc (d *FieldData) getPrimitive(k string, schema *FieldSchema) (interface{}, bool, error) {\n\traw, ok := d.Raw[k]\n\tif !ok {\n\t\treturn nil, false, nil\n\t}\n\n\tswitch t := schema.Type; t {\n\tcase TypeBool:\n\t\tvar result bool\n\t\tif err := mapstructure.WeakDecode(raw, \u0026result); err != nil {\n\t\t\treturn nil, false, err\n\t\t}\n\t\treturn result, true, nil\n```\n\nNotably, `WeakDecode(...)` eventually calls one of the decode helpers, which surfaces the original value:\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L679-L686\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L726-L730\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L783-L787\n\n\u0026 more.\n\n### PoC\n\nTo reproduce with OpenBao:\n\n```\n$ podman run -p 8300:8300 openbao/openbao:latest server -dev -dev-root-token-id=root -dev-listen-address=0.0.0.0:8300\n```\n\nand in a new tab:\n\n```\n$ BAO_TOKEN=root BAO_ADDR=http://localhost:8300 bao auth enable userpass\nSuccess! Enabled userpass auth method at: userpass/\n$ curl -X PUT -H \"X-Vault-Request: true\" -H \"X-Vault-Token: root\" -d '{\"password\":{\"asdf\":\"my-sensitive-value\"}}' \"http://localhost:8300/v1/auth/userpass/users/adsf\"\n{\"errors\":[\"error converting input for field \\\"password\\\": '' expected type 'string', got unconvertible type 'map[string]interface {}', value: 'map[asdf:my-sensitive-value]'\"]}\n```\n\n### Impact\n\nThis is an information disclosure bug with little mitigation. See https://discuss.hashicorp.com/t/hcsec-2025-09-vault-may-expose-sensitive-information-in-error-logs-when-processing-malformed-data-with-the-kv-v2-plugin/74717 for a previous version. That version was fixed, but this is in the second part of that error message (starting at `'' expected a map, got 'string'` -- when the field type is `string` and a `map` is provided, we see the above information leak -- the previous example had a `map` type field with a `string` value provided).\n\nThis was rated 4.5 Medium by HashiCorp in the past iteration.","status":"published","published":"2025-06-27T16:24:59Z","modified":"2025-06-27T16:24:59Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-532"],"updated_at":"2026-11-02T14:38:47.835488Z"}],"osv":[{"id":"GHSA-fv92-fjc5-jj9h","title":"mapstructure May Leak Sensitive Information in Logs When Processing Malformed Data","description":"### Summary\n\nUse of this library in a security-critical context may result in leaking sensitive information, if used to process sensitive fields.\n\n### Details\n\nOpenBao (and presumably HashiCorp Vault) have surfaced error messages from `mapstructure` as follows:\n\nhttps://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L43-L50\n\n```go\n\t\t\t_, _, err := d.getPrimitive(field, schema)\n\t\t\tif err != nil {\n\t\t\t\treturn fmt.Errorf(\"error converting input for field %q: %w\", field, err)\n\t\t\t}\n```\n\nwhere this calls `mapstructure.WeakDecode(...)`: https://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L181-L193\n\n```go\n\nfunc (d *FieldData) getPrimitive(k string, schema *FieldSchema) (interface{}, bool, error) {\n\traw, ok := d.Raw[k]\n\tif !ok {\n\t\treturn nil, false, nil\n\t}\n\n\tswitch t := schema.Type; t {\n\tcase TypeBool:\n\t\tvar result bool\n\t\tif err := mapstructure.WeakDecode(raw, \u0026result); err != nil {\n\t\t\treturn nil, false, err\n\t\t}\n\t\treturn result, true, nil\n```\n\nNotably, `WeakDecode(...)` eventually calls one of the decode helpers, which surfaces the original value:\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L679-L686\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L726-L730\n\nhttps://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L783-L787\n\n\u0026 more.\n\n### PoC\n\nTo reproduce with OpenBao:\n\n```\n$ podman run -p 8300:8300 openbao/openbao:latest server -dev -dev-root-token-id=root -dev-listen-address=0.0.0.0:8300\n```\n\nand in a new tab:\n\n```\n$ BAO_TOKEN=root BAO_ADDR=http://localhost:8300 bao auth enable userpass\nSuccess! Enabled userpass auth method at: userpass/\n$ curl -X PUT -H \"X-Vault-Request: true\" -H \"X-Vault-Token: root\" -d '{\"password\":{\"asdf\":\"my-sensitive-value\"}}' \"http://localhost:8300/v1/auth/userpass/users/adsf\"\n{\"errors\":[\"error converting input for field \\\"password\\\": '' expected type 'string', got unconvertible type 'map[string]interface {}', value: 'map[asdf:my-sensitive-value]'\"]}\n```\n\n### Impact\n\nThis is an information disclosure bug with little mitigation. See https://discuss.hashicorp.com/t/hcsec-2025-09-vault-may-expose-sensitive-information-in-error-logs-when-processing-malformed-data-with-the-kv-v2-plugin/74717 for a previous version. That version was fixed, but this is in the second part of that error message (starting at `'' expected a map, got 'string'` -- when the field type is `string` and a `map` is provided, we see the above information leak -- the previous example had a `map` type field with a `string` value provided).\n\nThis was rated 4.5 Medium by HashiCorp in the past iteration.","status":"published","published":"2025-06-27T16:24:59Z","modified":"2026-09-10T03:50:25.089025634Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-532"],"updated_at":"2026-11-02T15:46:46.760785Z"},{"id":"GO-2025-3787","title":"May leak sensitive information in logs when processing malformed data in github.com/go-viper/mapstructure","description":"May leak sensitive information in logs when processing malformed data in github.com/go-viper/mapstructure","status":"published","published":"2025-07-28T19:56:54Z","modified":"2026-02-04T04:13:21.433029Z","updated_at":"2026-11-02T15:47:01.728182Z"}]}}