CVE-2026-62681: Orval: RCE via OpenAPI path -> unescaped request-URL template literal (backtick breakout)

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, an unescaped backtick in an OpenAPI path is emitted into request URL template literals generated for axios, fetch, react-query, and SWR clients without safe encoding. This permits attacker-controlled JavaScript to be evaluated when a generated request, URL-builder, or query-key function is called, resulting in code execution in the developer, CI, test, or application environment. The affected code is packages/core/src/getters/route.ts and route generation consumers. This issue is fixed in version 8.21.0.

From the GitHub advisory

Summary

Orval emits the OpenAPI path into the generated request URL as a TEMPLATE LITERAL ( /users/... ) without escaping the backtick character. A path containing a backtick closes the template literal and injects a concatenation expression that is evaluated when the generated URL/request/key function is called, executing attacker-controlled code. Affects the axios, fetch, react-query, and swr clients. Verified on Orval 8.19.0; survives Orval's default OpenAPI validation.

Details

The backtick in the path terminates the ... literal; + ( ) + runs as a live expression; a trailing backtick reopens a template literal so the file stays valid. The code runs whenever the generated request function, URL builder, or query-key function is called.

This is distinct from Orval's four published CVEs: CVE-2026-22785 (summary -> MCP server), CVE-2026-23947 / CVE-2026-25141 (x-enumDescriptions), and CVE-2026-24132 (const -> mock files). This is a different field (the route path) and a different sink (the request-URL template literal), which those advisories and their fixes do not cover.

Weakness type: CWE-94, CWE-116, CWE-1336.

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 published by GitHub_M
• 2026-08-21 — CVE record last updated
• 2026-09-03 — GitHub-reviewed advisory GHSA-fg9p-mrxr-hvq7 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-fg9p-mrxr-hvq7 github.com
2. CVE.org record CVE-2026-62681 cve.org
3. NVD entry CVE-2026-62681 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