CVE-2026-59886 is a denial-of-service vulnerability in the pyasn1 library affecting the univ.Real type. When decoding BER/CER/DER-encoded REAL values with very large exponents, converting these values to Python floats triggers excessive CPU and memory consumption, potentially hanging the process. This occurs during float conversion operations such as prettyPrint(), str(), comparisons, arithmetic, or explicit float() calls. The issue affects pyasn1 versions >=0.1.0 and <0.2.2_15 and is fixed in version 0.2.2_15.