GHSA-fv92-fjc5-jj9h – github.com/go-viper/mapstructure/v2

Package

Manager: go
Name: github.com/go-viper/mapstructure/v2
Vulnerable Version: >=0 <2.3.0

Severity

Level: Medium

CVSS v3.1: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

CVSS v4.0: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

EPSS: N/A pctlN/A

Details

mapstructure May Leak Sensitive Information in Logs When Processing Malformed Data ### Summary Use of this library in a security-critical context may result in leaking sensitive information, if used to process sensitive fields. ### Details OpenBao (and presumably HashiCorp Vault) have surfaced error messages from `mapstructure` as follows: https://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L43-L50 ```go _, _, err := d.getPrimitive(field, schema) if err != nil { return fmt.Errorf("error converting input for field %q: %w", field, err) } ``` where this calls `mapstructure.WeakDecode(...)`: https://github.com/openbao/openbao/blob/98c3a59c040efca724353ca46ca79bd5cdbab920/sdk/framework/field_data.go#L181-L193 ```go func (d *FieldData) getPrimitive(k string, schema *FieldSchema) (interface{}, bool, error) { raw, ok := d.Raw[k] if !ok { return nil, false, nil } switch t := schema.Type; t { case TypeBool: var result bool if err := mapstructure.WeakDecode(raw, &result); err != nil { return nil, false, err } return result, true, nil ``` Notably, `WeakDecode(...)` eventually calls one of the decode helpers, which surfaces the original value: https://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L679-L686 https://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L726-L730 https://github.com/go-viper/mapstructure/blob/1a66224d5e54d8757f63bd66339cf764c3292c21/mapstructure.go#L783-L787 & more. ### PoC To reproduce with OpenBao: ``` $ podman run -p 8300:8300 openbao/openbao:latest server -dev -dev-root-token-id=root -dev-listen-address=0.0.0.0:8300 ``` and in a new tab: ``` $ BAO_TOKEN=root BAO_ADDR=http://localhost:8300 bao auth enable userpass Success! Enabled userpass auth method at: userpass/ $ 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" {"errors":["error converting input for field \"password\": '' expected type 'string', got unconvertible type 'map[string]interface {}', value: 'map[asdf:my-sensitive-value]'"]} ``` ### Impact This 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). This was rated 4.5 Medium by HashiCorp in the past iteration.

Metadata

Created: 2025-06-27T16:24:59Z
Modified: 2025-06-27T16:24:59Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/06/GHSA-fv92-fjc5-jj9h/GHSA-fv92-fjc5-jj9h.json
CWE IDs: ["CWE-532"]
Alternative ID: N/A
Finding: F063
Auto approve: 1