Hermes WebUI before 0.51.443 contains a broken access control vulnerability in the /api/session endpoint that allows authenticated users to disclose cross-profile session transcripts. Attackers can bypass profile boundary checks by directly querying session IDs belonging to other profiles via GET /api/session?session_id=<foreign_id>&messages=1 to retrieve unauthorized conversation transcripts and metadata.
{
"cna_assigner": "VulnCheck",
"cwe_ids": [
"CWE-639"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55197.json"
}{
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "0.51.443"
}
],
"source": [
"AFFECTED_FIELD",
"DESCRIPTION",
"REFERENCES"
]
}