Common Weakness Enumeration

CWE-918

Allowed

Server-Side Request Forgery (SSRF)

Abstraction: Base · Status: Incomplete

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

4755 vulnerabilities reference this CWE, most recent first.

GHSA-FVJH-QJCJ-7CC6

Vulnerability from github – Published: 2022-05-24 16:54 – Updated: 2024-04-04 01:45
VLAI
Details

The nelio-ab-testing plugin before 4.5.11 for WordPress has SSRF in ajax/iesupport.php.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2016-10927"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2019-08-22T14:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "The nelio-ab-testing plugin before 4.5.11 for WordPress has SSRF in ajax/iesupport.php.",
  "id": "GHSA-fvjh-qjcj-7cc6",
  "modified": "2024-04-04T01:45:38Z",
  "published": "2022-05-24T16:54:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2016-10927"
    },
    {
      "type": "WEB",
      "url": "https://wordpress.org/plugins/nelio-ab-testing/#developers"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FVQ6-MX7C-4433

Vulnerability from github – Published: 2026-07-13 12:35 – Updated: 2026-07-13 12:35
VLAI
Details

Server-Side Request Forgery (SSRF) vulnerability in Themeisle Auto Featured Image (Auto Post Thumbnail) auto-post-thumbnail allows Server Side Request Forgery.This issue affects Auto Featured Image (Auto Post Thumbnail): from n/a through <= 5.0.4.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-61970"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-13T10:16:46Z",
    "severity": "MODERATE"
  },
  "details": "Server-Side Request Forgery (SSRF) vulnerability in Themeisle Auto Featured Image (Auto Post Thumbnail) auto-post-thumbnail allows Server Side Request Forgery.This issue affects Auto Featured Image (Auto Post Thumbnail): from n/a through \u003c= 5.0.4.",
  "id": "GHSA-fvq6-mx7c-4433",
  "modified": "2026-07-13T12:35:06Z",
  "published": "2026-07-13T12:35:06Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-61970"
    },
    {
      "type": "WEB",
      "url": "https://patchstack.com/database/Wordpress/Plugin/auto-post-thumbnail/vulnerability/wordpress-auto-featured-image-auto-post-thumbnail-plugin-5-0-4-server-side-request-forgery-ssrf-vulnerability?_s_id=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FVX3-G627-PHM2

Vulnerability from github – Published: 2019-04-18 14:27 – Updated: 2023-09-05 23:27
VLAI
Summary
Server-Side Request Forgery (SSRF) in com.ctrip.framework.apollo:apollo
Details

An SSRF vulnerability was found in an API from Ctrip Apollo through 1.4.0-SNAPSHOT. An attacker may use it to do an intranet port scan or raise a GET request via /system-info/health because the %23 substring is mishandled.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.ctrip.framework.apollo:apollo"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.3.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2019-10686"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2020-06-16T21:35:29Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "An SSRF vulnerability was found in an API from Ctrip Apollo through 1.4.0-SNAPSHOT. An attacker may use it to do an intranet port scan or raise a GET request via `/system-info/health` because the `%23` substring is mishandled.",
  "id": "GHSA-fvx3-g627-phm2",
  "modified": "2023-09-05T23:27:35Z",
  "published": "2019-04-18T14:27:42Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-10686"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ctripcorp/apollo/issues/2103"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-fvx3-g627-phm2"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ctripcorp/apollo"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Server-Side Request Forgery (SSRF) in com.ctrip.framework.apollo:apollo"
}

GHSA-FWCM-636P-68R5

Vulnerability from github – Published: 2021-02-08 19:16 – Updated: 2023-05-16 15:41
VLAI
Summary
Server-side request forgery in CarrierWave
Details

Impact

CarrierWave download feature has an SSRF vulnerability, allowing attacks to provide DNS entries or IP addresses that are intended for internal use and gather information about the Intranet infrastructure of the platform.

Patches

Upgrade to 2.1.1 or 1.3.2.

Workarounds

Using proper network segmentation and applying the principle of least privilege to outbound connections from application servers can reduce the severity of SSRF vulnerabilities. Ideally the vulnerable gem should run on an isolated server without access to any internal network resources or cloud metadata access.

References

Server-Side Request Forgery Prevention Cheat Sheet

For more information

If you have any questions or comments about this advisory: * Open an issue in CarrierWave repo * Email me at mit.shibuya@gmail.com

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "carrierwave"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.3.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "carrierwave"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "2.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-21288"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-02-08T18:51:29Z",
    "nvd_published_at": "2021-02-08T20:15:00Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n[CarrierWave download feature](https://github.com/carrierwaveuploader/carrierwave#uploading-files-from-a-remote-location) has an SSRF vulnerability, allowing attacks to provide DNS entries or IP addresses that are intended for internal use and gather information about the Intranet infrastructure of the platform.\n\n### Patches\nUpgrade to [2.1.1](https://rubygems.org/gems/carrierwave/versions/2.1.1) or [1.3.2](https://rubygems.org/gems/carrierwave/versions/1.3.2).\n\n### Workarounds\nUsing proper network segmentation and applying the principle of least privilege to outbound connections from application servers can reduce the severity of SSRF vulnerabilities. Ideally the vulnerable gem should run on an isolated server without access to any internal network resources or cloud metadata access.\n\n### References\n[Server-Side Request Forgery Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Server_Side_Request_Forgery_Prevention_Cheat_Sheet.html)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [CarrierWave repo](https://github.com/carrierwaveuploader/carrierwave)\n* Email me at [mit.shibuya@gmail.com](mailto:mit.shibuya@gmail.com)",
  "id": "GHSA-fwcm-636p-68r5",
  "modified": "2023-05-16T15:41:50Z",
  "published": "2021-02-08T19:16:26Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/carrierwaveuploader/carrierwave/security/advisories/GHSA-fwcm-636p-68r5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21288"
    },
    {
      "type": "WEB",
      "url": "https://github.com/carrierwaveuploader/carrierwave/commit/012702eb3ba1663452aa025831caa304d1a665c0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/carrierwaveuploader/carrierwave"
    },
    {
      "type": "WEB",
      "url": "https://github.com/carrierwaveuploader/carrierwave/blob/master/CHANGELOG.md#132---2021-02-08"
    },
    {
      "type": "WEB",
      "url": "https://github.com/carrierwaveuploader/carrierwave/blob/master/CHANGELOG.md#211---2021-02-08"
    },
    {
      "type": "WEB",
      "url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/carrierwave/CVE-2021-21288.yml"
    },
    {
      "type": "WEB",
      "url": "https://rubygems.org/gems/carrierwave"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Server-side request forgery in CarrierWave"
}

GHSA-FWCR-P45J-G3CW

Vulnerability from github – Published: 2022-05-17 02:41 – Updated: 2022-05-17 02:41
VLAI
Details

SSRF vulnerability in remotedownload.php in Allen Disk 1.6 allows remote authenticated users to conduct port scans and access intranet servers via a crafted file parameter.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2017-9307"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2017-05-31T04:29:00Z",
    "severity": "MODERATE"
  },
  "details": "SSRF vulnerability in remotedownload.php in Allen Disk 1.6 allows remote authenticated users to conduct port scans and access intranet servers via a crafted file parameter.",
  "id": "GHSA-fwcr-p45j-g3cw",
  "modified": "2022-05-17T02:41:56Z",
  "published": "2022-05-17T02:41:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2017-9307"
    },
    {
      "type": "WEB",
      "url": "https://github.com/s3131212/allendisk/issues/20"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FWFP-H68W-2HCR

Vulnerability from github – Published: 2026-05-27 00:31 – Updated: 2026-06-30 21:31
VLAI
Details

A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to send crafted requests to internal services by exploiting insufficient input validation in an upload endpoint. By injecting path traversal content into request parameters, an attacker could bypass the intended request flow and redirect internal API calls, potentially accessing internal services and exposing sensitive credentials. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.16.20, 3.17.17, 3.18.11, 3.19.8, 3.20.4, and 3.21.1. This vulnerability was reported via the GitHub Bug Bounty program.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-9312"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-27T00:16:39Z",
    "severity": "CRITICAL"
  },
  "details": "A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to send crafted requests to internal services by exploiting insufficient input validation in an upload endpoint. By injecting path traversal content into request parameters, an attacker could bypass the intended request flow and redirect internal API calls, potentially accessing internal services and exposing sensitive credentials. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.16.20, 3.17.17, 3.18.11, 3.19.8, 3.20.4, and 3.21.1. This vulnerability was reported via the GitHub Bug Bounty program.",
  "id": "GHSA-fwfp-h68w-2hcr",
  "modified": "2026-06-30T21:31:35Z",
  "published": "2026-05-27T00:31:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9312"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.20"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.17"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.11"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.8"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.4"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.1"
    },
    {
      "type": "WEB",
      "url": "https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-FWG4-Q55Q-W62P

Vulnerability from github – Published: 2023-11-21 00:30 – Updated: 2025-05-19 15:30
VLAI
Details

Book Stack version 23.10.2 allows filtering local files on the server. This is possible because the application is vulnerable to SSRF.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-6199"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-11-20T23:15:06Z",
    "severity": "HIGH"
  },
  "details": "Book Stack version 23.10.2 allows filtering local files on the server. This is possible because the application is vulnerable to SSRF.",
  "id": "GHSA-fwg4-q55q-w62p",
  "modified": "2025-05-19T15:30:29Z",
  "published": "2023-11-21T00:30:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-6199"
    },
    {
      "type": "WEB",
      "url": "https://fluidattacks.com/advisories/imagination"
    },
    {
      "type": "WEB",
      "url": "https://www.bookstackapp.com/blog/bookstack-release-v23-10-3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-FWHC-MM9Q-MQQ8

Vulnerability from github – Published: 2024-05-22 21:30 – Updated: 2024-05-23 14:18
VLAI
Summary
VuFind Server-Side Request Forgery (SSRF) vulnerability
Details

A Server-Side Request Forgery (SSRF) vulnerability in the /Cover/Show route (showAction in CoverController.php) in Open Library Foundation VuFind 2.4 through 9.1 before 9.1.1 allows remote attackers to access internal HTTP servers and perform Cross-Site Scripting (XSS) attacks by proxying arbitrary URLs via the proxy GET parameter.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "vufind/vufind"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.4"
            },
            {
              "fixed": "9.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-25737"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-05-23T14:13:15Z",
    "nvd_published_at": "2024-05-22T19:15:08Z",
    "severity": "CRITICAL"
  },
  "details": "A Server-Side Request Forgery (SSRF) vulnerability in the /Cover/Show route (showAction in CoverController.php) in Open Library Foundation VuFind 2.4 through 9.1 before 9.1.1 allows remote attackers to access internal HTTP servers and perform Cross-Site Scripting (XSS) attacks by proxying arbitrary URLs via the proxy GET parameter.",
  "id": "GHSA-fwhc-mm9q-mqq8",
  "modified": "2024-05-23T14:18:28Z",
  "published": "2024-05-22T21:30:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-25737"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vufind-org/vufind/commit/345d00f7d7f1c581f46742effdac70e803b3847b"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vufind-org/vufind/commit/51f2ddac0dc1047e6fd3b27e6d984b19e1601d00"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vufind-org/vufind"
    },
    {
      "type": "WEB",
      "url": "https://vufind.org/wiki/security:cve-2024-25737"
    }
  ],
  "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:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "VuFind Server-Side Request Forgery (SSRF) vulnerability"
}

GHSA-FWHW-CHW4-GH37

Vulnerability from github – Published: 2026-02-02 09:30 – Updated: 2026-02-02 21:23
VLAI
Summary
Keycloak Server-Side Request Forgery (SSRF) vulnerability
Details

A flaw was found in Keycloak’s CIBA feature where insufficient validation of client-configured backchannel notification endpoints could allow blind server-side requests to internal services.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.keycloak:keycloak-parent"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "26.5.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-1518"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-02T21:23:18Z",
    "nvd_published_at": "2026-02-02T08:16:06Z",
    "severity": "LOW"
  },
  "details": "A flaw was found in Keycloak\u2019s CIBA feature where insufficient validation of client-configured backchannel notification endpoints could allow blind server-side requests to internal services.",
  "id": "GHSA-fwhw-chw4-gh37",
  "modified": "2026-02-02T21:23:18Z",
  "published": "2026-02-02T09:30:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1518"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/security/cve/CVE-2026-1518"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2433727"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/keycloak/keycloak"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Keycloak Server-Side Request Forgery (SSRF) vulnerability"
}

GHSA-FWJQ-J8GC-2F24

Vulnerability from github – Published: 2022-06-24 00:00 – Updated: 2022-06-30 00:00
VLAI
Details

OneBlog v2.3.4 was discovered to contain a Server-Side Request Forgery (SSRF) vulnerability via the Logo parameter under the Link module.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2022-34013"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-06-23T17:15:00Z",
    "severity": "MODERATE"
  },
  "details": "OneBlog v2.3.4 was discovered to contain a Server-Side Request Forgery (SSRF) vulnerability via the Logo parameter under the Link module.",
  "id": "GHSA-fwjq-j8gc-2f24",
  "modified": "2022-06-30T00:00:37Z",
  "published": "2022-06-24T00:00:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-34013"
    },
    {
      "type": "WEB",
      "url": "https://gitee.com/yadong.zhang/DBlog/issues/I5CB2A"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

No mitigation information available for this CWE.

CAPEC-664: Server Side Request Forgery

An adversary exploits improper input validation by submitting maliciously crafted input to a target application running on a server, with the goal of forcing the server to make a request either to itself, to web services running in the server’s internal network, or to external third parties. If successful, the adversary’s request will be made with the server’s privilege level, bypassing its authentication controls. This ultimately allows the adversary to access sensitive data, execute commands on the server’s network, and make external requests with the stolen identity of the server. Server Side Request Forgery attacks differ from Cross Site Request Forgery attacks in that they target the server itself, whereas CSRF attacks exploit an insecure user authentication mechanism to perform unauthorized actions on the user's behalf.