How severe is CVE-2026-56409?

CVE-2026-56409 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over local access with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.

Is CVE-2026-56409 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-56409?

CVE-2026-56409 affects Libexpat Project Libexpat. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-56409?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-56409 have an EU (EUVD) identifier?

Yes. CVE-2026-56409 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38186.

When was CVE-2026-56409 published?

CVE-2026-56409 was published on 2026-06-21 and last updated on 2026-06-23.

CVE-2026-56409

CVE-2026-56409 is a medium-severity vulnerability in Libexpat Project Libexpat with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (1st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-38186
Weakness: CWE-190
Affected product: Libexpat Project Libexpat
Published: 2026-06-21
Last modified: 2026-06-23

Description

xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.

Frequently asked questions

What is CVE-2026-56409?: xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.
How severe is CVE-2026-56409?: CVE-2026-56409 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over local access with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2026-56409 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-56409?: CVE-2026-56409 affects Libexpat Project Libexpat. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-56409?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-56409 have an EU (EUVD) identifier?: Yes. CVE-2026-56409 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38186.
When was CVE-2026-56409 published?: CVE-2026-56409 was published on 2026-06-21 and last updated on 2026-06-23.

References

https://github.com/libexpat/libexpat/pull/1259

Affected products (1)

cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*

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