Security readout for executives and security teams
Plain-English summary
Rundeck installations before the fixed releases could let a logged-in user make the server run untrusted code through crafted YAML in plugins, ACL policies, or project archives. Rundeck Enterprise also had an authenticated POST path with no specific authorization requirement. This is high urgency where vulnerable Rundeck is reachable by users.
Executive priority
Treat as a high-priority remediation for any internet-facing or broadly accessible Rundeck instance. The business risk is server-side code execution by an authenticated user, which can affect automation systems that often hold operational credentials and access to production infrastructure.
Technical view
CVE-2021-39132 is a CWE-502 unsafe YAML deserialization flaw in Rundeck Community and Enterprise. Affected versions are below 3.3.14 and 3.4.0 through 3.4.2. The CVSS 3.1 score is 8.8 with low complexity, low privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely in organizations running vulnerable Rundeck versions with users allowed to upload zip-format plugins, ACL policy YAML, or project archives. Enterprise deployments have additional exposure from an authenticated POST path that the advisory says needs authentication but no specific authorization.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. Exploitation requires authentication, with specific authorization for plugin and ACL upload paths. The Enterprise-only POST issue requires authentication but no specific authorization, increasing concern for broad internal user exposure.
Researcher notes
The source bundle identifies multiple authenticated input paths but does not provide exploit details here. Keep validation focused on version, edition, authorization model, and upload/import activity. Do not assume unauthenticated exposure; the supplied evidence consistently requires authentication.
Mitigation direction
- Upgrade Rundeck to 3.3.14, 3.4.3, or a later fixed release.
- Prioritize Enterprise deployments because one path needs authentication but no specific authorization.
- Restrict plugin, ACL policy, and project archive upload permissions until upgraded.
- Allow only trusted administrators to manage system, project_acl, and system_acl resources.
- Review the Rundeck advisory and patch commit for vendor-specific guidance.
Validation and detection
- Inventory Rundeck Community and Enterprise versions across all environments.
- Confirm no instance runs below 3.3.14 or 3.4.0 through 3.4.2.
- Review who has system, project_acl, and system_acl create, update, or admin permissions.
- Check audit logs for recent plugin, ACL policy, and project archive uploads.
- For Enterprise, review authenticated POST activity around administrative or import-related endpoints.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-39132 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/rundeck/rundeck/security/advisories/GHSA-q4rf-3fhx-88pfCVE reference · x_refsource_CONFIRM
- https://github.com/rundeck/rundeck/commit/850d12e21d22833bc148b7f458d7cb5949f829b6CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.