CVE-2017-9228: Oniguruma Project Oniguruma

Critical severity, CVSS 9.8. EPSS: 6.3% chance of exploitation in the next 30 days.

An issue was discovered in Oniguruma 6.2.0, as used in Oniguruma-mod in Ruby through 2.4.1 and mbstring in PHP through 7.1.5. A heap out-of-bounds write occurs in bitset_set_range() during regular expression compilation due to an uninitialized variable from an incorrect state transition. An incorrect state transition in parse_char_class() could create an execution path that leaves a critical local variable uninitialized until it's used as an index, resulting in an out-of-bounds write memory corruption.

Affected products

• Oniguruma Project Oniguruma: version 6.2.0 only
• PHP PHP: from 5.6.0, before 5.6.31 (fixed in 5.6.31); from 7.0.0, before 7.0.21 (fixed in 7.0.21); from 7.1.0, before 7.1.7 (fixed in 7.1.7)

Published 2017-05-24. Last modified 2026-06-17.