Local JSON disclosure via BYONM path traversal
Published Jun 23, 2026 · Updated Jun 23, 2026
Path traversal in Deno before 2.7.12 allows local users to read JSON files outside the configured read scope through a hostile package. In BYONM mode, the CommonJS module resolver joins a package.json main value to the package directory without constraining the normalized result to that root, then loads the JSON without the --allow-read check. Exploitation requires manual node_modules mode, a restricted read scope, and an installed package containing a traversal entrypoint; exposure is limited to JSON files readable by the Deno process's OS user.
Summary
What happened
Path traversal in Deno before 2.7.12 allows local users to read JSON files outside the configured read scope through a hostile package. In BYONM mode, the CommonJS module resolver joins a package.json main value to the package directory without constraining the normalized result to that root, then loads the JSON without the --allow-read check. Exploitation requires manual node_modules mode, a restricted read scope, and an installed package containing a traversal entrypoint; exposure is limited to JSON files readable by the Deno process's OS user.
The record
- CVE
- CVE-2026-49406
- Published
- Jun 23, 2026
- Updated
- Jun 23, 2026
- Vendor
- Deno Land Inc.
- Product
- Deno
- Classifications
- CWE-22, CAPEC-126, T1005
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Jun 23, 2026CVE publishedPublication date reported by the CVE source.
- Jun 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.7.12
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.
Weakness, pattern, technique
Public exploit references
- Deno BYONM path-traversal proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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