CVE-2026-93990 [HIGH] – Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 i

Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.