Medium · published April 7, 2025
ts-asn1-der is a collection of utility classes to encode ASN.1 data following DER rule. Incorrect number DER encoding can lead to denial on service for absolute values in the range 2**31 -- 2**32 - 1. The arithmetic in the numBitLen didn't take into account that values in this range could result in a negative result upon applying the >> operator, leading to an infinite loop. The issue is patched in version 1.0.4. If upgrading is not an option, the issue can be mitigated by validating inputs to Asn1Integer to ensure that they are not smaller than -2**31 + 1 and no larger than 2**31 - 1.