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HIGH

CVE-2026-93990

CVSS v3

7.5

HIGH

EPSS Score

0.4 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

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.

Technical details

Published
2026-09-19
Last Modified
2026-09-21

Frequently asked questions

What is CVE-2026-93990?

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.

Is CVE-2026-93990 actively exploited?

Active exploitation of CVE-2026-93990 has not been confirmed. Its EPSS score was 0.4% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-93990?

CVE-2026-93990 has a CVSS v3 base score of 7.5 (HIGH severity).

Is CVE-2026-93990 affecting your environment?

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