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Vulnerabilities

Vulnerability · CVE-2026-93582

Authentication Bypass via Spoofed Remote-User Header in HTTP Basic Authentication

Published Oct 12, 2026 · catalog updated Oct 15, 2026 · OTRS GmbH (former OTRS AG) OTRS

Check if you run it

No confirmed exploitation is on record for CVE-2026-93582. EPSS is 0.39%. Act only if a listed version of OTRS GmbH (former OTRS AG) OTRS is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.39%
Remediation
Advisory link
Affected products
vendor OTRS GmbH (former OTRS AG) ((OTRS)) Community Edition · vendor OTRS GmbH (former OTRS AG) OTRS

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

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

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  • vendor OTRS GmbH (former OTRS AG) ((OTRS)) Community Editionversion unspecified
  • vendor OTRS GmbH (former OTRS AG) OTRSversion unspecified

How to fix CVE-2026-93582

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-93582. EPSS is 0.39%. Act only if a listed version of OTRS GmbH (former OTRS AG) OTRS is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-290: Authentication Bypass by Spoofing. EPSS 0.39%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 12, 2026 · CIRCL Vulnerability Lookup

    Detected

    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

  2. Oct 15, 2026 · CIRCL Vulnerability Lookup

    Updated

    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

Sources

  • CIRCL Vulnerability LookupVulnerability recordCVE-2026-93582

    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_

    vulnerability.circl.lu
  • CVE.orgVulnerability recordCVE-2026-93582

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-93582

    30-day exploitation probability 0.4%

    first.org

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.