Vulnerability-Lookup

GHSA-2R8J-R49X-M28R

Vulnerability from github – Published: 2026-09-02 15:34 – Updated: 2026-09-02 15:34

Details

The Yoast SEO Premium WordPress plugin before 27.6.1 does not sanitize control characters from redirect origins before writing them to the site's Apache configuration file when the file-based redirect mode is enabled, and the redirect-creation endpoint is reachable by users with only Author-level access. This allows such users to inject arbitrary newline-delimited Apache directives into the root .htaccess file. On Apache servers that honour PHP directives, the injection can be chained with the user's own media upload (a polyglot image carrying a PHP payload) and an auto_prepend_file directive to achieve Remote Code Execution.

Severity

6.6 (Medium)


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

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-10821"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-74"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-02T15:17:37Z",
    "severity": "MODERATE"
  },
  "details": "The Yoast SEO Premium WordPress plugin before 27.6.1 does not sanitize control characters from redirect origins before writing them to the site\u0027s Apache configuration file when the file-based redirect mode is enabled, and the redirect-creation endpoint is reachable by users with only Author-level access. This allows such users to inject arbitrary newline-delimited Apache directives into the root .htaccess file. On Apache servers that honour PHP directives, the injection can be chained with the user\u0027s own media upload (a polyglot image carrying a PHP payload) and an auto_prepend_file directive to achieve Remote Code Execution.",
  "id": "GHSA-2r8j-r49x-m28r",
  "modified": "2026-09-02T15:34:48Z",
  "published": "2026-09-02T15:34:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-10821"
    },
    {
      "type": "WEB",
      "url": "https://wpscan.com/vulnerability/2ddd8362-7248-48de-aab9-74c70e7d5dd6"
    },
    {
      "type": "WEB",
      "url": "https://yoast.com/yoast-seo-premium-may-26-2026"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-10821 (GCVE-0-2026-10821)

Vulnerability from cvelistv5 – Published: 2026-09-02 14:16 – Updated: 2026-09-02 14:57

Title

Yoast SEO Premium < 27.6.1 - Author+ Arbitrary .htaccess Directive Injection to RCE

Summary

Severity

6.6 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-02 14:48 UTC

CWE

CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Assigner

WPScan mitre root

References

2 references

URL	Tags
https://wpscan.com/vulnerability/2ddd8362-7248-48…	exploitvdb-entrytechnical-description
https://yoast.com/yoast-seo-premium-may-26-2026/	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
Unknown	Yoast SEO Premium	Affected: 0 , < 27.6.1 (semver)

Credits

Tin Pham (TF1T) Trong Pham (dtro) Hao Ngo WPScan

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-10821",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-02T14:48:28.117001Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-74",
                "description": "CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component (\u0027Injection\u0027)",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-02T14:57:38.690Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Yoast SEO Premium",
          "vendor": "Unknown",
          "versions": [
            {
              "lessThan": "27.6.1",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Tin Pham (TF1T)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Trong Pham (dtro)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Hao Ngo"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "WPScan"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The Yoast SEO Premium WordPress plugin before 27.6.1 does not sanitize control characters from redirect origins before writing them to the site\u0027s Apache configuration file when the file-based redirect mode is enabled, and the redirect-creation endpoint is reachable by users with only Author-level access. This allows such users to inject arbitrary newline-delimited Apache directives into the root .htaccess file. On Apache servers that honour PHP directives, the injection can be chained with the user\u0027s own media upload (a polyglot image carrying a PHP payload) and an auto_prepend_file directive to achieve Remote Code Execution."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 6.6,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component (\u0027Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-02T14:16:44.007Z",
        "orgId": "1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81",
        "shortName": "WPScan"
      },
      "references": [
        {
          "tags": [
            "exploit",
            "vdb-entry",
            "technical-description"
          ],
          "url": "https://wpscan.com/vulnerability/2ddd8362-7248-48de-aab9-74c70e7d5dd6/"
        },
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://yoast.com/yoast-seo-premium-may-26-2026/"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Yoast SEO Premium \u003c 27.6.1 - Author+ Arbitrary .htaccess Directive Injection to RCE",
      "x_generator": {
        "engine": "WPScan CVE Generator"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81",
    "assignerShortName": "WPScan",
    "cveId": "CVE-2026-10821",
    "datePublished": "2026-09-02T14:16:44.007Z",
    "dateReserved": "2026-06-04T07:41:54.109Z",
    "dateUpdated": "2026-09-02T14:57:38.690Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

GHSA-2R8J-R49X-M28R

CVE-2026-10821 (GCVE-0-2026-10821)

Tags

Sightings

Nomenclature