CVE-2026-88064 (GCVE-0-2026-88064)
Vulnerability from cvelistv5 – Published: 2026-09-16 14:13 – Updated: 2026-09-16 15:46
VLAI
EPSS
VEX
Title
Backstage: Improper input validation in TechDocs MkDocs configuration
Summary
Backstage is an open framework for building developer portals. Prior to 1.14.6 and from 1.15.0 until 1.15.4, the @backstage/plugin-techdocs-node package insufficiently validates mkdocs.yml supplied by an authenticated user who can register or modify a TechDocs source. Unsafe Python YAML tags, markdown_extensions names and configuration, theme options, and extra_templates values can reach the documentation generator and cause unintended code execution. The resulting impact is limited to the files, credentials, network access, and other resources available to the TechDocs backend or build container. This issue is fixed in versions 1.14.6 and 1.15.4.
Severity
8.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-16 15:46 UTC
CWE
Assigner
References
8 references
| URL | Tags |
|---|---|
| https://github.com/backstage/backstage/security/a… | x_refsource_CONFIRM |
| https://github.com/backstage/backstage/commit/017… | x_refsource_MISC |
| https://github.com/backstage/backstage/commit/02c… | x_refsource_MISC |
| https://github.com/backstage/backstage/commit/251… | x_refsource_MISC |
| https://github.com/backstage/backstage/commit/a7d… | 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
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"id": "CVE-2026-88064",
"options": [
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"role": "CISA Coordinator",
"timestamp": "2026-09-16T15:46:28.697895Z",
"version": "2.0.3"
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"title": "CISA ADP Vulnrichment"
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{
"product": "backstage",
"vendor": "backstage",
"versions": [
{
"status": "affected",
"version": "\u003c 1.14.6"
},
{
"status": "affected",
"version": "\u003e= 1.15.0, \u003c 1.15.4"
}
]
}
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}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
}
],
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{
"cweId": "CWE-20",
"description": "CWE-20: Improper Input Validation",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-1336",
"description": "CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine",
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],
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"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/backstage/backstage/security/advisories/GHSA-292q-8mf5-h6g3",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/backstage/backstage/security/advisories/GHSA-292q-8mf5-h6g3"
},
{
"name": "https://github.com/backstage/backstage/commit/017ace52d9b327ededc6704cf17799c875ae0f29",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/commit/017ace52d9b327ededc6704cf17799c875ae0f29"
},
{
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"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb"
},
{
"name": "https://github.com/backstage/backstage/commit/25125ee727a3de3418a8fa6a9e458cd5b73ecf26",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/commit/25125ee727a3de3418a8fa6a9e458cd5b73ecf26"
},
{
"name": "https://github.com/backstage/backstage/commit/a7d995f11a5d27f0efbdbe8bb6c21b06988c79c9",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/commit/a7d995f11a5d27f0efbdbe8bb6c21b06988c79c9"
},
{
"name": "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d"
},
{
"name": "https://github.com/backstage/backstage/releases/tag/v1.50.5",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/releases/tag/v1.50.5"
},
{
"name": "https://github.com/backstage/backstage/releases/tag/v1.54.6",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/releases/tag/v1.54.6"
}
],
"source": {
"advisory": "GHSA-292q-8mf5-h6g3",
"discovery": "UNKNOWN"
},
"title": "Backstage: Improper input validation in TechDocs MkDocs configuration"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-88064",
"datePublished": "2026-09-16T14:13:26.950Z",
"dateReserved": "2026-09-09T21:22:45.434Z",
"dateUpdated": "2026-09-16T15:46:46.830Z",
"state": "PUBLISHED"
},
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"date": "2026-09-24",
"epss": "0.00875",
"percentile": "0.57197"
},
"nvd": {
"cve": {
"affected": [
{
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{
"product": "backstage",
"vendor": "backstage",
"versions": [
{
"status": "affected",
"version": "\u003c 1.14.6"
},
{
"status": "affected",
"version": "\u003e= 1.15.0, \u003c 1.15.4"
}
]
}
],
"source": "security-advisories@github.com"
}
],
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"lang": "en",
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}
],
"id": "CVE-2026-88064",
"lastModified": "2026-09-16T16:17:19.897",
"metrics": {
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"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
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"version": "2.0.3"
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"published": "2026-09-16T15:18:04.297",
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"url": "https://github.com/backstage/backstage/commit/017ace52d9b327ededc6704cf17799c875ae0f29"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/backstage/backstage/commit/25125ee727a3de3418a8fa6a9e458cd5b73ecf26"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/backstage/backstage/commit/a7d995f11a5d27f0efbdbe8bb6c21b06988c79c9"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/backstage/backstage/releases/tag/v1.50.5"
},
{
"source": "security-advisories@github.com",
"url": "https://github.com/backstage/backstage/releases/tag/v1.54.6"
},
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"url": "https://github.com/backstage/backstage/security/advisories/GHSA-292q-8mf5-h6g3"
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"vulnrichment": {
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"Technical Impact": "total"
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"role": "CISA Coordinator",
"timestamp": "2026-09-16T15:46:28.697895Z",
"version": "2.0.3"
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
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"title": "CISA ADP Vulnrichment"
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"cna": {
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"product": "backstage",
"vendor": "backstage",
"versions": [
{
"status": "affected",
"version": "\u003c 1.14.6"
},
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"status": "affected",
"version": "\u003e= 1.15.0, \u003c 1.15.4"
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}
],
"metrics": [
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"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
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"confidentialityImpact": "HIGH",
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"scope": "UNCHANGED",
"userInteraction": "NONE",
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],
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"dateUpdated": "2026-09-16T14:13:26.950Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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},
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},
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},
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"tags": [
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],
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},
{
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"tags": [
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],
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},
{
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"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/backstage/backstage/releases/tag/v1.54.6"
}
],
"source": {
"advisory": "GHSA-292q-8mf5-h6g3",
"discovery": "UNKNOWN"
},
"title": "Backstage: Improper input validation in TechDocs MkDocs configuration"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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"cveId": "CVE-2026-88064",
"datePublished": "2026-09-16T14:13:26.950Z",
"dateReserved": "2026-09-09T21:22:45.434Z",
"dateUpdated": "2026-09-16T15:46:46.830Z",
"state": "PUBLISHED"
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}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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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.
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.
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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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