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GHSA-2464-8j7c-4cjm
No affected components available
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
_, _, 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
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 via strconv helpers:
https://github.com/go-viper/mapstructure/blob/8c61ec1924fcfa522f9fc6b4618c672db61d1a38/mapstructure.go#L720-L727
https://github.com/go-viper/mapstructure/blob/8c61ec1924fcfa522f9fc6b4618c672db61d1a38/mapstructure.go#L791-L798
https://github.com/go-viper/mapstructure/blob/8c61ec1924fcfa522f9fc6b4618c672db61d1a38/decode_hooks.go#L180
& more. These are different code paths than are fixed in the previous iteration at https://github.com/go-viper/mapstructure/security/advisories/GHSA-fv92-fjc5-jj9h.
PoC
To reproduce with OpenBao:
$ podman run --pull=always -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 '{"ttl":"asdf"}' "http://localhost:8200/v1/auth/userpass/users/asdf"
--> server logs:
2025-06-25T21:32:25.101-0500 [ERROR] core: failed to run existence check: error="error converting input for field \"ttl\": time: invalid duration \"asdf\""
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.
The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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