CVE-2026-93990 (GCVE-0-2026-93990)

Vulnerability from cvelistv5 – Published: 2026-09-19 22:58 – Updated: 2026-09-28 16:11
VLAI
Title
Expat before 2.8.5 Malformed UTF-16 Acceptance via Unchecked Surrogate
Summary
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.
Severity
8.7 (High)
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
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-21 15:10 UTC
CWE
  • CWE-176 - Improper Handling of Unicode Encoding
Assigner
VulnCheck CNA under the mitre root
CNA scorecard B 84/100 over 7140 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
libexpat libexpat Affected: 0 , < 2.8.5 (semver)
Unaffected: 2.8.5 (semver)
    cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-09-18 00:00
Credits
Kartik Kenchi (netliomax25-code)
Show details on NVD website
To clipboard 

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