Vulnerability-Lookup

GHSA-8W7Q-29MW-GF5C

Vulnerability from github – Published: 2026-10-07 16:23 – Updated: 2026-10-07 16:23

Summary

Backstage: Improper validation of MkDocs theme configuration in TechDocs

Details

Impact

When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in mkdocs.yml that cause arbitrary code execution during the documentation build process.

Patches

Patched in @backstage/plugin-techdocs-node version 1.15.4

Workarounds

Configure TechDocs with techdocs.generator.runIn: 'docker' instead of 'local' to provide container isolation, though this does not fully mitigate the risk.
Restrict write access to repositories registered in the Backstage catalog to trusted users.

Severity

7.7 (High)


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

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@backstage/plugin-techdocs-node"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.15.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-106509"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1336",
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-07T16:23:30Z",
    "nvd_published_at": "2026-10-06T22:17:06Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nWhen TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in `mkdocs.yml` that cause arbitrary code execution during the documentation build process.\n\n### Patches\n\nPatched in `@backstage/plugin-techdocs-node` version `1.15.4`\n\n### Workarounds\n\n- Configure TechDocs with `techdocs.generator.runIn: \u0027docker\u0027` instead of `\u0027local\u0027` to provide container isolation, though this does not fully mitigate the risk.\n- Restrict write access to repositories registered in the Backstage catalog to trusted users.",
  "id": "GHSA-8w7q-29mw-gf5c",
  "modified": "2026-10-07T16:23:30Z",
  "published": "2026-10-07T16:23:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/security/advisories/GHSA-8w7q-29mw-gf5c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-106509"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/backstage/backstage"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/releases/tag/v1.50.5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/releases/tag/v1.54.6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Backstage: Improper validation of MkDocs theme configuration in TechDocs"
}

CVE-2026-106509 (GCVE-0-2026-106509)

Vulnerability from cvelistv5 – Published: 2026-10-06 21:50 – Updated: 2026-10-07 18:01

Title

Backstage: Improper validation of MkDocs theme configuration in TechDocs

Summary

Backstage is an open framework for building developer portals. Prior to 1.14.6, the @backstage/plugin-techdocs-node package is affected by improper validation of mkdocs theme configuration in techdocs. When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in mkdocs.yml that cause arbitrary code execution during the documentation build process. This issue is fixed in versions 1.14.6 and 1.15.4.

Severity

7.7 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-07 18:01 UTC

CWE

CWE-94 - Improper Control of Generation of Code ('Code Injection')
CWE-1336 - Improper Neutralization of Special Elements Used in a Template Engine

Assigner

GitHub_M mitre root Scorecard

References

5 references

URL	Tags
https://github.com/backstage/backstage/security/a…	x_refsource_CONFIRM
https://github.com/backstage/backstage/commit/02c…	x_refsource_MISC
https://github.com/backstage/backstage/commit/a90…	x_refsource_MISC
https://github.com/backstage/backstage/releases/t…	x_refsource_MISC
https://github.com/backstage/backstage/releases/t…	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
backstage	backstage	Affected: < 1.50.5 Affected: >= 1.51.0-next.0, < 1.54.6
@backstage	plugin-techdocs-node	Affected: < 1.14.6 Affected: >= 1.15.0, < 1.15.4

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-106509",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-07T18:01:39.138438Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
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          "product": "backstage",
          "vendor": "backstage",
          "versions": [
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        {
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          "versions": [
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              "version": "\u003c 1.14.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.15.0, \u003c 1.15.4"
            }
          ]
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      ],
      "descriptions": [
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          "lang": "en",
          "value": "Backstage is an open framework for building developer portals. Prior to 1.14.6, the @backstage/plugin-techdocs-node package is affected by improper validation of mkdocs theme configuration in techdocs. When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in mkdocs.yml that cause arbitrary code execution during the documentation build process. This issue is fixed in versions 1.14.6 and 1.15.4."
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      "metrics": [
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          "cvssV3_1": {
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            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 7.7,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "LOW",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L",
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      ],
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            {
              "cweId": "CWE-1336",
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              "type": "CWE"
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          "tags": [
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          "tags": [
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          "url": "https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb"
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        {
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          "url": "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d"
        },
        {
          "name": "https://github.com/backstage/backstage/releases/tag/v1.50.5",
          "tags": [
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          "url": "https://github.com/backstage/backstage/releases/tag/v1.50.5"
        },
        {
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      "title": "Backstage: Improper validation of MkDocs theme configuration in TechDocs"
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  "cveMetadata": {
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    "datePublished": "2026-10-06T21:50:07.721Z",
    "dateReserved": "2026-10-06T18:46:47.767Z",
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  },
  "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.

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.

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