fix: validate protocol scheme names in setAsDefaultProtocolClient#50141
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MarshallOfSound merged 1 commit intomainfrom Mar 9, 2026
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fix: validate protocol scheme names in setAsDefaultProtocolClient#50141MarshallOfSound merged 1 commit intomainfrom
setAsDefaultProtocolClient#50141MarshallOfSound merged 1 commit intomainfrom
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On Windows, `app.setAsDefaultProtocolClient(protocol)` directly concatenates the protocol string into the registry key path with no validation. A protocol name containing `\` could write to an arbitrary subkey under `HKCU\Software\Classes\`, potentially hijacking existing protocol handlers. To fix this, add `Browser::IsValidProtocolScheme()` which validates that a protocol name conforms to the RFC 3986 scheme grammar: scheme = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." ) This rejects backslashes, forward slashes, whitespace, and any other characters not permitted in URI schemes.
deepak1556
approved these changes
Mar 9, 2026
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| for (size_t i = 1; i < scheme.size(); ++i) { | ||
| const char c = scheme[i]; | ||
| if (!base::IsAsciiAlpha(c) && !base::IsAsciiDigit(c) && c != '+' && | ||
| c != '-' && c != '.') { | ||
| LOG(ERROR) << "Protocol scheme contains invalid character: '" << c << "'"; | ||
| return false; | ||
| } | ||
| } |
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minor nit: should we simplify the loop similar to https://source.chromium.org/chromium/chromium/src/+/main:chrome/browser/external_protocol/auto_launch_protocols_policy_handler.cc;l=37-40 ?
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Release Notes Persisted
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This was referenced Mar 9, 2026
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I have automatically backported this PR to "41-x-y", please check out #50155 |
Contributor
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I have automatically backported this PR to "39-x-y", please check out #50156 |
Contributor
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I have automatically backported this PR to "38-x-y", please check out #50157 |
Contributor
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I have automatically backported this PR to "40-x-y", please check out #50158 |
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Description of Change
On Windows,
app.setAsDefaultProtocolClient(protocol)directly concatenates the protocol string into the registry key path with no validation. A protocol name containing\could write to an arbitrary subkey underHKCU\Software\Classes\, potentially hijacking existing protocol handlers.To fix this, add
Browser::IsValidProtocolScheme()which validates that a protocol name conforms to the RFC 3986 scheme grammar:This rejects backslashes, forward slashes, whitespace, and any other characters not permitted in URI schemes.
Checklist
npm testpassesRelease Notes
Notes: Added validation to protocol client methods to reject protocol names that do not conform to the RFC 3986 URI scheme grammar.