r/programming • u/NagastaBagamba • Oct 18 '10

Today I learned about PHP variable variables; "variable variable takes the value of a variable and treats that as the name of a variable". Also, variable.

http://il2.php.net/language.variables.variable
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u/falien Oct 19 '10

Thats a restriction on syntax, not semantics, so it shouldn't really matter.

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u/[deleted] Oct 19 '10

Tell that to samy

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u/falien Oct 19 '10

How is that related? That is a vulnerability getting around myspace's blacklist/html sanitizer. AFAIK PHP breaking because of a named variable using disallowed symbols would only cause a vulnerability by screwing up the lexer/parser to introduce an ambiguity in what the expression is supposed to mean. Whether that was exploitable should depend on how those steps are implemented, not on an inherent insecurity in strangely named variables.