Source-code disclosure via dev-middleware origin-check bypass
Published Jun 12, 2026 · Updated Jun 12, 2026
Source-code disclosure in Nuxt 3.15.4 through 3.21.5 and 4.0.0-alpha.1 through 4.4.5 allows remote attackers to read built source. The webpack and rspack dev-middleware same-origin check trusts Sec-Fetch-Mode and Sec-Fetch-Site, so non-trustworthy origins lacking those headers reach built module scripts. Exploitation requires a predictable host, a non-loopback dev-server binding, and a developer using a browser without local-network restrictions to open a malicious site on the same network.
Summary
What happened
Source-code disclosure in Nuxt 3.15.4 through 3.21.5 and 4.0.0-alpha.1 through 4.4.5 allows remote attackers to read built source. The webpack and rspack dev-middleware same-origin check trusts Sec-Fetch-Mode and Sec-Fetch-Site, so non-trustworthy origins lacking those headers reach built module scripts. Exploitation requires a predictable host, a non-loopback dev-server binding, and a developer using a browser without local-network restrictions to open a malicious site on the same network.
The record
- CVE
- CVE-2026-45670
- Published
- Jun 12, 2026
- Updated
- Jun 12, 2026
- Vendor
- Nuxt
- Product
- Nuxt
- Classifications
- CWE-749, T1189
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 12, 2026CVE publishedPublication date reported by the CVE source.
- Jun 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 3.15.4, < 3.21.6
- Affected versionversion=>= 4.0.0-alpha.1, < 4.4.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Upstream cross-origin built-source proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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