Impact

The redis-cli command line tool and redis-sentinel service may be vulnerable to integer overflow when parsing specially crafted large multi-bulk network replies. This is a result of a vulnerability in the underlying hiredis library which does not perform an overflow check before calling the calloc() heap allocation function.

This issue only impacts systems with heap allocators that do not perform their own overflow checks. Most modern systems do and are therefore not likely to be affected. Furthermore, by default redis-sentinel uses the jemalloc allocator which is also not vulnerable.

Patches

The problem is fixed in Redis versions 6.2.6, 6.0.16 and 5.0.14.

Credit

This issue was discovered and reported by Microsoft Vulnerability Research.

For more information

If you have any questions or comments about this advisory:

• Open an issue in the Redis repository
• Email us at redis@redis.io