Expat before 2.8.5 Malformed UTF-16 Acceptance via Unchecked Surrogate
Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following code unit, causing Expat to pass unpaired surrogates to applications built with XML_UNICODE and to silently replace input characters in other builds.
CVE-2026-93990
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-93990
libexpat
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://github.com/libexpat/libexpat",
"vendor": "libexpat",
"product": "libexpat",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "2.8.5",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "2.8.5",
"versionType": "semver"
}
],
"packageURL": "pkg:github/libexpat/libexpat",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-93990
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #3189 · Revision 1
- Added to Heist Feed
- Publisher date