[Mime][String] Reject objects in typed-string properties during __unserialize#64345
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nicolas-grekas merged 1 commit intoMay 23, 2026
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[Mime][String] Reject objects in typed-string properties during __unserialize#64345nicolas-grekas merged 1 commit intosymfony:7.4symfony/symfony:7.4from nicolas-grekas:harden-unserialize-trampolines-7.4nicolas-grekas/symfony:harden-unserialize-trampolines-7.4Copy head branch name to clipboard
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This was referenced May 27, 2026
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Same class of issue as #64343 on 6.4: a
__unserialize(array $data)that assigns$data[...]to a typedstring(or union-with-string) property lets PHP's type coercion invoke__toString()on any attacker-supplied object before the value is stored. A post-assignmentis_string()guard runs too late.This PR covers the surface that exists on 7.4 and is not addressed in #64343:
$dataString\UnicodeStringstring $stringMime\Part\TextPart?string $charset,string $subtype,?string $disposition,?string $name,string $encodingMime\Part\SMimePartiterable|string $body,string $type,string $subtypeUnion types that include
string(e.g.iterable|string) also trigger__toString()coercion; forSMimePart::$bodythe guard isinstanceof \Stringable && !is_iterable($body)since PHP prefers the iterable branch when an object satisfies both.Each
__unserialize()now validates the shape of the raw$databefore any assignment, throwingBadMethodCallExceptionon mismatch.UnicodeString's existing post-check is moved to run before the assignment;TextPartandSMimePartgain explicit pre-checks for every typed-string slot (in every key-prefix variant: bare,\0Class\0..., and\0*\0...).The 6.4 hardening for
Route,CompiledRoute,Window,SlidingWindow,TokenBucket, andEmaillands on 7.4 via the upmerge.