{"id":"CVE-2026-93990","summary":"Expat through 2.8.4 Malformed UTF-16 Acceptance via Unchecked Surrogate","details":"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.","modified":"2026-09-20T11:47:30.263681487Z","published":"2026-09-19T22:58:11.224Z","database_specific":{"cwe_ids":["CWE-176"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93990.json","cna_assigner":"VulnCheck"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93990.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93990"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/expat-through-2.8.4-malformed-utf-16-acceptance-via-unchecked-surrogate"},{"type":"FIX","url":"https://github.com/libexpat/libexpat/commit/ff6e1d7e750bbe245178f51a47a965dc8342861a"},{"type":"FIX","url":"https://github.com/libexpat/libexpat/pull/1282"},{"type":"PACKAGE","url":"https://github.com/libexpat/libexpat"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/libexpat/libexpat","events":[{"introduced":"0"},{"fixed":"12cf0b1f25f026a022fe728ad8f7e3d017285b80"},{"fixed":"ff6e1d7e750bbe245178f51a47a965dc8342861a"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"2.8.4"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["R_2_8_4","R_2_8_3","R_2_8_2","R_2_8_1","R_2_8_0","R_2_7_5","R_2_7_4","R_2_7_3","R_2_7_2","R_2_7_1","R_2_7_0","R_2_6_4","R_2_6_3","R_2_6_2","R_2_6_1","R_2_6_0","R_2_5_0","R_2_4_9","R_2_4_8","R_2_4_7","R_2_4_6","R_2_4_5","R_2_4_4","R_2_4_3","R_2_4_2","R_2_4_1","R_2_4_0","R_2_3_0","R_2_2_10","R_2_2_9","R_2_2_8","R_2_2_7","R_2_2_6","R_2_2_5","R_2_2_4","R_2_2_3","R_2_2_2","R_2_2_1","R_2_2_0","R_2_1_1","R_2_1_0","R_2_0_1","R_2_0_0","R_1_95_8","R_1_95_7","R_1_95_6","R_1_95_5","R_1_95_4","R_1_95_3","R_1_95_2","R_1_95_0","libexpat-alpha-1","start","sourceforge_init","jclark-orig","V20000512","V19991013","V19990728","V19990709","V19990626","V1_1","V19990425","V1990307","V19990109","V19981231","V19981122","V1_0","beta4","beta3","beta2","REC1_0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93990.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}]}