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CVE-2026-25896

Naturalintelligence Fast-xml-parser cross-site scripting (XSS)

9.3 CRITICALPublic exploitEPSS 0.50%
  1. Published20 Feb 2026

Description

fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. From 4.1.3to before 5.3.5, a dot (.) in a DOCTYPE entity name is treated as a regex wildcard during entity replacement, allowing an attacker to shadow built-in XML entities (<, >, &, ", ') with arbitrary values. This bypasses entity encoding and leads to XSS when parsed output is rendered. This vulnerability is fixed in 5.3.5.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityLow
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N

Affected products

Naturalintelligence Fast-xml-parser≥ 4.1.3 < 5.3.5

Remediation

Fixed in
Naturalintelligence Fast-xml-parser≥ 5.3.5

References

and 5 more references

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Frequently asked

Is CVE-2026-25896 being actively exploited?

CVE-2026-25896 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.50%.

How severe is CVE-2026-25896?

CVE-2026-25896 has a CVSS 3.1 base score of 9.3, rated critical. EPSS estimates a 0.50% probability of exploitation.

Which products are affected by CVE-2026-25896?

Affected products include Naturalintelligence Fast-xml-parser.

How do I fix CVE-2026-25896?

Upgrade affected software to a fixed version, for example Naturalintelligence Fast-xml-parser 5.3.5 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-25896 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.