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An exploitable Use After Free vulnerability exists in the CharProcs parsing functionality of NitroPDF. A specially crafted PDF can cause a type confusion, resulting in a Use After Free. An attacker can craft a malicious PDF to trigger this vulnerability.
An exploitable Use After Free vulnerability exists in the CharProcs parsing functionality of NitroPDF. A specially crafted PDF can cause a type confusion, resulting in a Use After Free. An attacker can craft a malicious PDF to trigger this vulnerability.
CVSS 3.1 Base Score 7.8. CVSS Attack Vector: local. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).
CVSS 2.0 Base Score 6.8. CVSS Attack Vector: network. CVSS Attack Complexity: medium. CVSS Vector: (AV:N/AC:M/Au:N/C:P/I:P/A:P).
The following Perl code is intended to look up the privileges for user ID's between 0 and 3, by performing an access of the $UserPrivilegeArray reference. It is expected that only userID 3 is an admin (since this is listed in the third element of the array).
print "\$UserPrivilegeArray = $UserPrivilegeArray\n";print "Regular user!\n";print "Admin!\n";In this case, the programmer intended to use "$UserPrivilegeArray->{$userID}" to access the proper position in the array. But because the subscript was omitted, the "user" string was compared to the scalar representation of the $UserPrivilegeArray reference, which might be of the form "ARRAY(0x229e8)" or similar.
Since the logic also "fails open" (CWE-636), the result of this bug is that all users are assigned administrator privileges.
While this is a forced example, it demonstrates how type confusion can have security consequences, even in memory-safe languages.
The following example demonstrates the weakness.
}free(buf3R2);The following code illustrates a use after free error:
}free(ptr);logError("operation aborted before commit", ptr);When an error occurs, the pointer is immediately freed. However, this pointer is later incorrectly used in the logError function.
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