Vulnerability-Lookup

CVE-2026-93582 (GCVE-0-2026-93582)

Vulnerability from cvelistv5 – Published: 2026-10-12 06:49 – Updated: 2026-10-12 06:49

Title

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

Summary

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

Severity

9.4 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

CWE

CWE-290 - Authentication Bypass by Spoofing

Assigner

OTRS CNA under the mitre root

CNA scorecard B 75/100 over 18 records in the last 180 days details

References

1 reference

URL	Tags
https://otrs.com/release-notes/otrs-security-advi…

Impacted products

2 products

Vendor	Product	Version	CPE status
OTRS GmbH (former OTRS AG)	OTRS	Unaffected: 7.0.x Unaffected: 8.0.x Unaffected: 2023.x Unaffected: 2024.x Unaffected: 2025.x Unaffected: 2026.x	guessed
OTRS GmbH (former OTRS AG)	((OTRS)) Community Edition	Affected: 6.x	guessed

Date Public

2026-10-12 07:00

Credits

Special thanks to Mokrane ABDELMALEK (via Ghent University VDP programme) for finding this vulnerability

Show details on NVD website

JSON

To clipboard

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          "vendor": "OTRS GmbH (former OTRS AG)",
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              "status": "unaffected",
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            {
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              "value": "\u003cp\u003eThe HTTP Basic Authentication modules in ((OTRS)) Community Edition 6 and prior accept the authenticated username from either the \u003ccode\u003eREMOTE_USER\u003c/code\u003e or \u003ccode\u003eHTTP_REMOTE_USER\u003c/code\u003e environment variable.\u0026nbsp;In CGI and mod_perl based deployments, HTTP request headers may be mapped to corresponding \u003ccode\u003eHTTP_*\u003c/code\u003e environment variables. As a result, an unauthenticated remote attacker can supply a crafted \u003ccode\u003eRemote-User\u003c/code\u003e request header which is exposed to the application as \u003ccode\u003eHTTP_REMOTE_USER\u003c/code\u003e.\u0026nbsp;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.\u003c/p\u003e\u003cp\u003eThe 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.\u0026nbsp;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 \u003ccode\u003eHTTP_*\u003c/code\u003e environment variables.\u003c/p\u003e\u003cp\u003eOTRS 7 and later are not affected by this attack vector due to the\u0026nbsp;use of Mojolicious/Hypnotoad and does not expose arbitrary request headers through \u003ccode\u003e%ENV\u003c/code\u003e in the manner required for exploitation. The supported \u003ccode\u003eREMOTE_USER\u003c/code\u003e mechanism additionally requires validation through the configured SSO shared secret. The unused \u003ccode\u003eHTTP_REMOTE_USER\u003c/code\u003e fallback has nevertheless been removed as a security-hardening measure.\u003c/p\u003e\u003cp\u003ePlease note that ((OTRS)) Community Edition 6.x and before are vulnerable. Products based on the ((OTRS)) Community Edition also very likely to be affected\u003cbr\u003e\u003c/p\u003e"
            }
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        }
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      "impacts": [
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          "capecId": "CAPEC-22",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-22 Exploiting Trust in Client"
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      "metrics": [
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            "baseScore": 9.4,
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            "scope": "UNCHANGED",
            "userInteraction": "NONE",
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              "description": "CWE-290 Authentication Bypass by Spoofing",
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        "orgId": "2e1bf29f-dc29-4ed8-830c-7b9348b6f0e8",
        "shortName": "OTRS"
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      "references": [
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          "url": "https://otrs.com/release-notes/otrs-security-advisory-2026-18/"
        }
      ],
      "solutions": [
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          "supportingMedia": [
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              "base64": false,
              "type": "text/html",
              "value": "Update to latest version of OTRS (2026.7.1. or later)."
            }
          ],
          "value": "Update to latest version of OTRS (2026.7.1. or later)."
        }
      ],
      "source": {
        "advisory": "OSA-2026-18",
        "defect": [
          "SecOPS#2026091710000411",
          "Issue#5466"
        ],
        "discovery": "USER"
      },
      "title": "Authentication Bypass via Spoofed Remote-User Header in HTTP Basic Authentication",
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    "assignerShortName": "OTRS",
    "cveId": "CVE-2026-93582",
    "datePublished": "2026-10-12T06:49:38.903Z",
    "dateReserved": "2026-09-18T10:57:10.801Z",
    "dateUpdated": "2026-10-12T06:49:38.903Z",
    "state": "PUBLISHED"
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                "defaultStatus": "unaffected",
                "product": "OTRS",
                "vendor": "OTRS GmbH (former OTRS AG)",
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                  {
                    "status": "unaffected",
                    "version": "7.0.x"
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                  {
                    "status": "unaffected",
                    "version": "8.0.x"
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                  {
                    "status": "unaffected",
                    "version": "2023.x"
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                  {
                    "status": "unaffected",
                    "version": "2024.x"
                  },
                  {
                    "status": "unaffected",
                    "version": "2025.x"
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                  {
                    "status": "unaffected",
                    "version": "2026.x"
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          }
        ],
        "id": "CVE-2026-93582",
        "lastModified": "2026-10-12T07:16:37.717",
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                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L",
                "version": "3.1"
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              "exploitabilityScore": 3.9,
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              "source": "security@otrs.com",
              "type": "Secondary"
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        "published": "2026-10-12T07:16:37.717",
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            "type": "Secondary"
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}

FKIE_CVE-2026-93582

Vulnerability from fkie_nvd - Published: 2026-10-12 07:16 - Updated: 2026-10-12 07:16

Severity

9.4 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

Summary

References

	URL	Tags
	security@otrs.com	https://otrs.com/release-notes/otrs-security-advisory-2026-18/

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "OTRS",
          "vendor": "OTRS GmbH (former OTRS AG)",
          "versions": [
            {
              "status": "unaffected",
              "version": "7.0.x"
            },
            {
              "status": "unaffected",
              "version": "8.0.x"
            },
            {
              "status": "unaffected",
              "version": "2023.x"
            },
            {
              "status": "unaffected",
              "version": "2024.x"
            },
            {
              "status": "unaffected",
              "version": "2025.x"
            },
            {
              "status": "unaffected",
              "version": "2026.x"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "((OTRS)) Community Edition",
          "vendor": "OTRS GmbH (former OTRS AG)",
          "versions": [
            {
              "status": "affected",
              "version": "6.x"
            }
          ]
        }
      ],
      "source": "security@otrs.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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.\u00a0In 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.\u00a0When 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.\u00a0Exploitation 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\u00a0use 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"
    }
  ],
  "id": "CVE-2026-93582",
  "lastModified": "2026-10-12T07:16:37.717",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 9.4,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
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}

GHSA-PRJ2-J7V3-MHCV

Vulnerability from github – Published: 2026-10-12 09:31 – Updated: 2026-10-12 09:31

Details

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

Severity

9.4 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-93582"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-290"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-12T07:16:37Z",
    "severity": "CRITICAL"
  },
  "details": "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.\u00a0In 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.\u00a0When 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.\u00a0Exploitation 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\u00a0use 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",
  "id": "GHSA-prj2-j7v3-mhcv",
  "modified": "2026-10-12T09:31:21Z",
  "published": "2026-10-12T09:31:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93582"
    },
    {
      "type": "WEB",
      "url": "https://otrs.com/release-notes/otrs-security-advisory-2026-18"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-93582 (GCVE-0-2026-93582)

FKIE_CVE-2026-93582

GHSA-PRJ2-J7V3-MHCV

Tags

Sightings

Nomenclature

Related by attack behaviour