CVE-2026-93582 Authentication Bypass via Spoofed Remote-User Header in HTTP Basic Authentication
Attackers can bypass authentication in OTRS Community Edition 6 by spoofing the Remote-User header, gaining unauthorized access to data and configuration.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-93582?
CVE-2026-93582 is a critical authentication bypass vulnerability in ((OTRS)) Community Edition, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
The 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.
OTRS 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.
Please note that ((OTRS)) Community Edition 6.x and before are vulnerable. Products based on the ((OTRS)) Community Edition also very likely to be affected
Weakness: CWE-290
Which versions are affected by CVE-2026-93582?
How do I fix CVE-2026-93582?
No fix has been published for CVE-2026-93582 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-93582 being exploited?
There is no known exploitation of CVE-2026-93582 in the wild and no public exploit code.
Sources
Also known as GHSA-prj2-j7v3-mhcv, UBUNTU-CVE-2026-93582.