CVE-2026-25896
XSS via DOCTYPE shadowing in fast-xml-parser <5.3.5
Is CVE-2026-25896 being exploited?
Not confirmed. CVE-2026-25896 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.46% probability of exploitation in the next 30 days.
How severe is CVE-2026-25896?
CVE-2026-25896 is rated Critical with a CVSS score of 9.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-25896?
Yes. A fix has been recorded for CVE-2026-25896. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-25896 affect?
CVE-2026-25896 affects fast-xml-parser (Node.js/JS) <5.3.5. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-25896?
Upgrade to 5.3.5 or later
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
XSS: crafted XML parsed by untrusted input can render scripts when output is displayed.
Patch when possible
- affected>= 5.0.0 and < 5.3.5
- affected>= 4.1.3 and < 4.5.4
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.