@backstage/plugin-techdocs-node: TechDocs Mkdocs Configuration Key Enables Arbitrary Code Execution
Summary
| CVE | CVE-2026-29186 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-07 15:15:55 UTC |
| Updated | 2026-06-30 03:18:08 UTC |
| Description | Backstage is an open framework for building developer portals. Prior to version 1.14.3, this is a configuration bypass vulnerability that enables arbitrary code execution. The @backstage/plugin-techdocs-node package uses an allowlist to filter dangerous MkDocs configuration keys during the documentation build process. A gap in this allowlist allows attackers to craft an mkdocs.yml that causes arbitrary Python code execution, completely bypassing TechDocs' security controls. This issue has been patched in version 1.14.3. |
Risk And Classification
Primary CVSS: v3.1 9.8 CRITICAL from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.007820000 probability, percentile 0.514910000 (date 2026-07-02)
Problem Types: CWE-74 | CWE-434 | CWE-791 | CWE-434 CWE-434: Unrestricted Upload of File with Dangerous Type | CWE-74 CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') | CWE-791 Incomplete Filtering of Special Elements
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | ADP | CVSS | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L |
| 3.1 | [email protected] | Secondary | 7.7 | HIGH | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L |
| 3.1 | CNA | DECLARED | 7.7 | HIGH | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Linuxfoundation | Backstage Plugin-techdocs-node | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Backstage | Backstage | affected < 1.14.3 | Not specified |
| ADP | Red Hat | Red Hat Developer Hub 1.8 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Developer Hub 1.9 | Not specified | Not specified |
| ADP | Red Hat | Self-service Automation Portal 2 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-29186 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:9742 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29186.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:13826 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| github.com/backstage/backstage/security/advisories/GHSA-928r-fm4v-mvrw | [email protected] | github.com | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-03-07T16:01:40.949Z | Reported to Red Hat. |
| ADP | 2026-03-07T15:03:51.422Z | Made public. |
Solutions
ADP: RHSA-2026:9742: Red Hat Developer Hub 1.8
ADP: RHSA-2026:13826: Red Hat Developer Hub 1.9
Workarounds
ADP: To mitigate this issue, enable docker isolation by updating the Backstage configuration to use 'runIn: docker' instead of 'runIn: local', confining the arbitrary Python code execution to a containerized environment. Additionally, limit commit access to repositories tracked by Backstage to trusted contributors only, and enforce mandatory pull request (PR) reviews for any modifications made to the mkdocs.yml file.