Security readout for executives and security teams
Plain-English summary
CVE-2021-25927 affects the JavaScript package safe-flat versions 2.0.0 and 2.0.1. A flaw called prototype pollution may let an unauthenticated attacker disrupt service and could lead to remote code execution. Business risk is highest where this package processes untrusted input in internet-facing applications.
Executive priority
Treat as high-priority dependency remediation for internet-facing or API-driven Node.js services. The severity is critical, but urgency should be based on whether affected versions are present and reachable by untrusted users.
Technical view
The CVE describes CWE-1321 prototype pollution in safe-flat 2.0.0 through 2.0.1. The assigned CVSS 3.1 score is 9.8 with network attack vector, low complexity, no privileges, and no user interaction. Sources indicate denial of service impact and possible remote code execution, but do not provide confirmed exploit activity.
Likely exposure
Exposure is limited to applications or services that include safe-flat 2.0.0 or 2.0.1 directly or transitively. Risk increases if untrusted JSON, request bodies, or object keys can reach the package.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. The CVSS vector indicates remote, unauthenticated exploitation is plausible when vulnerable code is reachable, but the bundle does not prove real-world abuse.
Researcher notes
The public bundle establishes affected versions, CWE, CVSS, and impact class. It does not include exploit proof, active exploitation evidence, or a named fixed release. Validate reachability before escalating from vulnerable dependency to exploitable application issue.
Mitigation direction
- Inventory direct and transitive safe-flat dependencies across applications.
- Prioritize replacement or remediation of safe-flat 2.0.0 and 2.0.1.
- Review upstream advisory and commit for vendor-supported fix guidance.
- Restrict untrusted input paths that reach object flattening logic.
- Redeploy rebuilt packages after dependency remediation.
Validation and detection
- Check package-lock, yarn.lock, pnpm-lock, and SBOMs for safe-flat 2.0.0 or 2.0.1.
- Use SCA tooling to flag CVE-2021-25927 in application builds.
- Confirm whether vulnerable safe-flat functions process external input.
- Verify remediated builds no longer include affected versions.
- Review dependency trees to catch transitive reintroduction.
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-1321: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-25927 mapping review
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Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/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:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25927CVE reference · x_refsource_MISC
- https://github.com/jessie-codes/safe-flat/commit/4b9b7db976bba8c968354f4315f5f9c219b7cbf3CVE 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.
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.