CVE-2026-119197 is a denial-of-service vulnerability in pyasn1 versions 0.6.4 and earlier affecting the decoding of binary-encoded ASN.1 REAL values with large mantissas. The decoding process has quadratic time complexity due to inefficient byte-wise processing, causing excessive CPU consumption. This impacts BER, CER, and DER decoders that use the vulnerable RealPayloadDecoder. The vulnerability allows an attacker who can supply crafted ASN.1 input containing REAL values to cause CPU exhaustion during decoding. The issue is fixed in pyasn1 version 0.6.5 by replacing the inefficient loop with a more efficient integer conversion. Until patched, applications should limit or reject attacker-controlled ASN.1 input with REAL values.