Is there a public exploit for CVE-2026-66046?

No public exploit for CVE-2026-66046 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-66046?

CVE-2026-66046 scores CVSS 8.7 (v4.0), rated high. EPSS puts the chance of exploitation in the next 30 days at 0.74%.

What does CVE-2026-66046 affect?

CVE-2026-66046 affects libexpat project libexpat.

8.7 High

Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in…

CVE-2026-66046

Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.

Assessment

CVSS: 8.7 (v4.0)
Severity: High
EPSS: 0.74% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 18 August 2026
Last updated: 8 November 2026
Affected: libexpat project · libexpat
Assigner: VulnCheck

CVSS vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

At the source

EUVD (ENISA)

References

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