{"id":"CVE-2026-106558","aliases":["EUVD-2026-94371","GHSA-qmw3-745m-w99g"],"status":"published","title":"Backstage: Improper validation of TechDocs MkDocs configuration","description":"Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdown_extensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation source may bypass TechDocs sanitization and cause Python objects to be imported and instantiated in the generator runtime, leading to arbitrary code execution. Earlier fixes in versions 1.14.6 and 1.15.4 did not fully address the supported mapping representation of markdown_extensions. Impact is greatest when documentation generation runs with backend credentials, filesystem access, or internal network access. This issue is fixed in versions 1.14.8, 1.15.6, and 2.0.1.","severity":{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00469,"percentile":0.41057,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-502"],"published":"2026-10-07T14:45:25Z","modified":"2026-10-28T02:30:42Z","fixes":[{"ecosystem":"npm","package":"@backstage/plugin-techdocs-node","fixed_in":["1.15.4"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@backstage/plugin-techdocs-node","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.15.4"}]}]},{"source":"osv","ecosystem":"npm","package":"@backstage/plugin-techdocs-node","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.15.4"}]}]}],"products":[{"vendor":"@backstage","product":"plugin-techdocs-node"},{"vendor":"backstage","product":"backstage"},{"vendor":"linuxfoundation","product":"backstage"},{"vendor":"linuxfoundation","product":"backstage_plugin-techdocs-node"}],"references":[{"url":"https://github.com/backstage/backstage/security/advisories/GHSA-qmw3-745m-w99g","tags":["x_refsource_CONFIRM","Mitigation","Vendor Advisory","advisory","web"]},{"url":"https://github.com/backstage/backstage/commit/32723a0fe4e12ed80535fc65d5331765c55aa91b","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://github.com/backstage/backstage/commit/944edb51c8524d3664b18f2d57ba101b1c93b709","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://github.com/backstage/backstage/commit/f18e9abcc6051491862b15e4fc60e69f8d52310c","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://github.com/backstage/backstage/releases/tag/v1.50.7","tags":["x_refsource_MISC","Patch","Release Notes","web"]},{"url":"https://github.com/backstage/backstage/releases/tag/v1.54.9","tags":["x_refsource_MISC","Patch","Release Notes","web"]},{"url":"https://github.com/backstage/backstage/releases/tag/v1.55.2","tags":["x_refsource_MISC","Patch","Release Notes","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-106558","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-qmw3-745m-w99g"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/106xxx/CVE-2026-106558.json","tags":["advisory"]},{"url":"https://github.com/backstage/backstage","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-106558","title":"Backstage: Improper validation of TechDocs MkDocs configuration","description":"Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdown_extensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation source may bypass TechDocs sanitization and cause Python objects to be imported and instantiated in the generator runtime, leading to arbitrary code execution. Earlier fixes in versions 1.14.6 and 1.15.4 did not fully address the supported mapping representation of markdown_extensions. Impact is greatest when documentation generation runs with backend credentials, filesystem access, or internal network access. This issue is fixed in versions 1.14.8, 1.15.6, and 2.0.1.","status":"published","published":"2026-10-07T14:45:25.679Z","modified":"2026-10-10T02:27:17.131Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-502"],"updated_at":"2026-11-02T14:20:04.156238Z"}],"euvd":[{"id":"EUVD-2026-94371","description":"Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdown_extensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation source may bypass TechDocs sanitization and cause Python objects to be imported and instantiated in the generator runtime, leading to arbitrary code execution. Earlier fixes in versions 1.14.6 and 1.15.4 did not fully address the supported mapping representation of markdown_extensions. Impact is greatest when documentation generation runs with backend credentials, filesystem access, or internal network access. This issue is fixed in versions 1.14.8, 1.15.6, and 2.0.1.","status":"published","published":"2026-10-07T14:45:25Z","modified":"2026-10-10T02:27:17Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T17:27:24.157251Z"}],"ghsa":[{"id":"GHSA-qmw3-745m-w99g","title":"Backstage: Improper validation of TechDocs MkDocs configuration","description":"### Impact\n\nAn attacker who can provide configuration to a TechDocs build may execute code in the generator runtime. Impact is greatest when documentation generation runs with backend credentials or host access.\n\n### Patches\n\nPatched in `@backstage/plugin-techdocs-node` version `1.15.4`.\n\n### Workarounds\n\nUse external TechDocs generation in an isolated environment without sensitive credentials or host access. Restrict and review changes to documentation configuration before generation.","status":"published","published":"2026-10-07T18:03:12Z","modified":"2026-10-07T18:03:15Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-502"],"updated_at":"2026-11-02T14:41:28.013673Z"}],"nvd":[{"id":"CVE-2026-106558","description":"Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdown_extensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation source may bypass TechDocs sanitization and cause Python objects to be imported and instantiated in the generator runtime, leading to arbitrary code execution. Earlier fixes in versions 1.14.6 and 1.15.4 did not fully address the supported mapping representation of markdown_extensions. Impact is greatest when documentation generation runs with backend credentials, filesystem access, or internal network access. This issue is fixed in versions 1.14.8, 1.15.6, and 2.0.1.","status":"published","published":"2026-10-07T15:17:15.713Z","modified":"2026-10-13T14:25:12.163Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-502"],"updated_at":"2026-11-02T14:12:54.809359Z"}],"osv":[{"id":"CVE-2026-106558","title":"Backstage: Improper validation of TechDocs MkDocs configuration","description":"Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdown_extensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation source may bypass TechDocs sanitization and cause Python objects to be imported and instantiated in the generator runtime, leading to arbitrary code execution. Earlier fixes in versions 1.14.6 and 1.15.4 did not fully address the supported mapping representation of markdown_extensions. Impact is greatest when documentation generation runs with backend credentials, filesystem access, or internal network access. This issue is fixed in versions 1.14.8, 1.15.6, and 2.0.1.","status":"published","published":"2026-10-07T14:45:25.679Z","modified":"2026-10-28T02:30:42.200568374Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-502"],"updated_at":"2026-11-02T15:44:54.583213Z"},{"id":"GHSA-qmw3-745m-w99g","title":"Backstage: Improper validation of TechDocs MkDocs configuration","description":"### Impact\n\nAn attacker who can provide configuration to a TechDocs build may execute code in the generator runtime. Impact is greatest when documentation generation runs with backend credentials or host access.\n\n### Patches\n\nPatched in `@backstage/plugin-techdocs-node` version `1.15.4`.\n\n### Workarounds\n\nUse external TechDocs generation in an isolated environment without sensitive credentials or host access. Restrict and review changes to documentation configuration before generation.","status":"published","published":"2026-10-07T18:03:12Z","modified":"2026-10-07T18:15:12.165363848Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-502"],"updated_at":"2026-11-02T15:46:54.760124Z"}]}}