CVE-2025-30403

CVE-2025-30403 is a high-severity vulnerability with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

A heap-buffer-overflow vulnerability is possible in mvfst via a specially crafted message during a QUIC session. This issue affects mvfst versions prior to v2025.07.07.00.

Frequently asked questions

What is CVE-2025-30403?
A heap-buffer-overflow vulnerability is possible in mvfst via a specially crafted message during a QUIC session. This issue affects mvfst versions prior to v2025.07.07.00.
How severe is CVE-2025-30403?
CVE-2025-30403 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2025-30403 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-30403?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-30403 have an EU (EUVD) identifier?
Yes. CVE-2025-30403 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-21179.
When was CVE-2025-30403 published?
CVE-2025-30403 was published on 2025-07-11 and last updated on 2026-06-17.

References