title: Buffer underflow in bc_shift_addsub
description: In PHP versions 7.2.x below 7.2.26, 7.3.x below 7.3.13 and 7.4.0, PHP bcmath extension functions on some systems, including Windows, can be tricked into reading beyond the allocated space by supplying it with string containing characters that are identified as numeric by the OS but aren't ASCII numbers. This can read to disclosure of the content of some memory locations.
problem types: CWE-125 Out-of-bounds Read
affected:
{
product: PHP
vendor: PHP Group
versions:
lessThan: 7.2.26, status: affected, version: 7.2.x, versionType: custom
lessThan: 7.3.13, status: affected, version: 7.3.x, versionType: custom
lessThan: 7.4.1, status: affected, version: 7.4.x, versionType: custom
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 3.7
baseSeverity: LOW
confidentialityImpact: LOW
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
version: 3.1
]