CVE-2026-71867: Orval: RCE via schema property name -> computed-property-key injection in the MSW mock generator

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.7%, percentile 51: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 51% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes orval (npm) < 8.21.0, fixed in 8.21.0. Check your lockfile, including transitive dependencies.

What it is

Orval generates type-safe JavaScript clients in TypeScript from OpenAPI v3 and Swagger v2 specifications. Prior to 8.21.0, a single quote in a schema property name is emitted into single-quoted object keys in generated MSW mock factories without safe encoding. This permits attacker-controlled JavaScript to be evaluated when the generated mock factory is called by tests or an MSW handler, resulting in code execution in the developer, CI, test, or application environment. The affected code is packages/core/src/getters/keys.ts function getKey and MSW mock generation. This issue is fixed in version 8.21.0.

From the GitHub advisory

Summary

orval, when generating MSW mocks (output.mock: true), emits each schema property name as a single-quoted object key in the mock factory WITHOUT escaping the single quote. A ' in a property name closes the key and lands in object-literal context, where an injected computed property key [expr] is evaluated when the mock factory is called (e.g. in tests / MSW handlers) -> RCE. The property name is a pure data field. Verified on orval 8.19.0 / Node.

Details

Safe elsewhere: the zod schema double-quotes the property name; the TS interface key is a type (DoS only). Distinct from orval's $ref / route-path / server-url / zod-default findings.

PoC

Weakness type: CWE-89, CWE-95.

Product: orval (npm) · Assigned by: GitHub_M · Published: 2026-08-19

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.65% probability of exploitation activity in the next 30 days; percentile 51.

Timeline

• 2026-08-19 — CVE record last updated
• 2026-08-19 — CVE record published by GitHub_M
• 2026-09-03 — GitHub-reviewed advisory GHSA-2w86-xfrc-g85r published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-2w86-xfrc-g85r github.com
2. CVE.org record CVE-2026-71867 cve.org
3. NVD entry CVE-2026-71867 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com

Critical npm advisories · Today’s Security Digest