| Title | garycourt uri-js 4.4.1 Missing Undefined Check on Mailto URI 'to' Header Parser |
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| Description | While auditing uri-js's scheme handlers for exception safety, I noticed the mailto handler's query-header parser has four branches (to, subject, body, default) that all handle a missing header value the same way, except one. The to branch skips the guard and calls .split(",") directly on a value that can be undefined, so any mailto URI with a bare to token in the query crashes URI.parse() with an uncaught TypeError. |
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| Source | ⚠️ https://github.com/garycourt/uri-js/issues/103 |
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| User | Yu Bao from PayPal Cyber Security Team (UID 99838) |
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| Submission | 09/02/2026 09:43 (28 days ago) |
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| Moderation | 09/30/2026 16:07 (28 days later) |
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| Status | Accepted |
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| VulDB entry | 412124 [garycourt uri-js up to 4.4.1 Mailto Header src/schemes/mailto.ts URI.parse uncaught exception] |
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| Points | 20 |
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