Velocity.js: Remote Code Execution via property-read to Function constructor (bypass of CVE-2026-44966 fix)
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-94.
Summary
Velocity.js is a JavaScript implementation of the Apache Velocity template engine. Prior to 2.1.7, the earlier fix for CVE-2026-44966 filtered constructor, __proto__, and prototype only in the #set assignment handler in src/compile/set.ts, while property-read expressions in src/compile/references.ts remained unfiltered. The getReferences() flow called getAttributes(), whose property access allowed an attacker-controlled template to traverse constructor.constructor to the JavaScript Function constructor. The #set handler validated only the assignment target and did not inspect the right-hand property-read expression, allowing arbitrary shell commands, environment-variable access, cloud-credential access, and internal-network access in the server process. This issue is fixed in version 2.1.7.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| shepherdwind | velocity.js | before 2.1.7 | 2.1.7 | Patch available | CNA |
| — | velocityjs (npm) | before 2.1.7 | 2.1.7 | Patch available | GHSA-7gfh-x38p-prh3 |
- velocity.js Vendorshepherdwind Affected before 2.1.7 Fixed in 2.1.7 Patch available CNA
- velocityjs (npm) Vendor— Affected before 2.1.7 Fixed in 2.1.7 Patch available GHSA-7gfh-x38p-prh3
Remediation
- Fix · CNA velocity.js (shepherdwind) Fixed in 2.1.7
- Fix · GHSA-7gfh-x38p-prh3 velocityjs (npm) Fixed in 2.1.7 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
Not affected: 1 product
- Red Hat Fuse 7
Timeline
- 2026-10-02 Threatist record created from CVE-2026-73649
- 2026-10-03 Alias added: GHSA-7gfh-x38p-prh3
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-10-23 Affected versions changed · Red Hat
References
Other 5
- https://github.com/shepherdwind/velocity.js/security/advisories/GHSA-7gfh-x38p-prh3
- https://github.com/shepherdwind/velocity.js/pull/192
- https://github.com/shepherdwind/velocity.js/commit/f8e47a6c4607249b9c967d3a1ced959b4dd64dba
- https://github.com/shepherdwind/velocity.js/releases/tag/v2.1.7
- https://github.com/shepherdwind/velocity.js
More shepherdwind vulnerabilities
- TI-2026-32828 Velocity.js: Prototype Pollution in #set path assignment CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-73649 · CVE Program
- CVE-2026-73649 · NVD
- FIRST EPSS
- GHSA-7gfh-x38p-prh3 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-73649 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences