CVE-2026-93990 Expat - XML Injection

Expat through 2.8.4 contains an XML injection vulnerability caused by failure to validate low surrogates following high surrogates in UTF-16 input, letting attackers craft malformed UTF-16 sequences to hide markup characters, exploit requires crafted UTF-16 encoded XML.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.40% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
XML Injection
Impact
Data Tampering
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Published
19 September 2026
Updated
15 October 2026
Weakness
CWE-176

Vendor fix

Update to the latest version beyond 2.8.4.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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