CVE-2026-68906 libIEC61850: Infinite loop and out-of-bounds read in ACSE parseUserInformation when parsing a malformed AARE PDU

libIEC61850 is an open-source implementation of IEC 61850 client and server protocols including MMS, GOOSE, Sampled Values, and R-Session. Prior to 1.6.2, parseUserInformation in src/mms/isoacse/acse.c checks len for zero before validating the negative bufPos returned by BerDecoderdecodeLength fo...