Out-of-Bounds Read Vulnerability in HHVM Stream Implementations

CVE-2019-3557 · HIGH Severity

AV:N/AC:L/AU:N/C:P/I:P/A:P

The implementations of streams for bz2 and php://output improperly implemented their readImpl functions, returning -1 consistently. This behavior caused some stream functions, such as stream_get_line, to trigger an out-of-bounds read when operating on such malformed streams. The implementations were updated to return valid values consistently. This affects all supported versions of HHVM (3.30 and 3.27.4 and below).

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