{"id":"CVE-2026-93582","published":"2026-10-12T07:16:37.717","lastModified":"2026-10-15T20:38:44.050","description":"The HTTP Basic Authentication modules in ((OTRS)) Community Edition 6 and prior accept the authenticated username from either the REMOTE_USER or HTTP_REMOTE_USER environment variable. In CGI and mod_perl based deployments, HTTP request headers may be mapped to corresponding HTTP_* environment variables. As a result, an unauthenticated remote attacker can supply a crafted Remote-User request header which is exposed to the application as HTTP_REMOTE_USER. When HTTP Basic Authentication is configured as the authentication backend, OTRS trusts this value as an already authenticated username and does not perform an additional password verification. An attacker may therefore authenticate through the Generic Interface as an existing agent or customer user without knowing the corresponding credentials.\n\nThe resulting privileges depend on the account being impersonated. Successful exploitation may allow access to confidential information and modification of data or configuration with the permissions of the affected user. Exploitation requires HTTP Basic Authentication to be configured as an authentication backend and a web server environment in which attacker-controlled HTTP headers are exposed through the corresponding HTTP_* environment variables.\n\nOTRS 7 and later are not affected by this attack vector due to the use of Mojolicious/Hypnotoad and does not expose arbitrary request headers through %ENV in the manner required for exploitation. The supported REMOTE_USER mechanism additionally requires validation through the configured SSO shared secret. The unused HTTP_REMOTE_USER fallback has nevertheless been removed as a security-hardening measure.\n\nPlease note that ((OTRS)) Community Edition 6.x and before are vulnerable. Products based on the ((OTRS)) Community Edition also very likely to be affected","cvssScore":9.4,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L","cwes":["CWE-290"],"vendors":[],"products":[],"references":[{"url":"https://otrs.com/release-notes/otrs-security-advisory-2026-18/","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"OTRS Community Edition 6 and earlier incorrectly trust authenticated usernames from HTTP headers, allowing attackers to impersonate users without valid credentials through HTTP Basic Authentication.","exploitability":"Easy to exploit when HTTP Basic Authentication is configured with CGI or mod_perl deployments that expose attacker-controlled headers as environment variables, requiring only a single crafted HTTP header.","blast_radius":"High impact as attackers can access confidential data and modify system configuration with permissions of any impersonated user account, potentially leading to full system compromise.","remediation":"Upgrade to OTRS Community Edition 7 or later, which uses Mojolicious/Hypnotoad and is not affected by this vulnerability.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["auth-bypass","http-header","web","authentication"],"model":"garnet-coder","analyzedAt":"2026-10-12T08:51:19.084Z"}}