A heap-buffer-overflow vulnerability is possible in mvfst via a specially crafted message during a QUIC session.

published 2025-07-11 15 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-21179

cvss: 8.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 links 1

Facebook mvfst v2025.07.07.00

github.com/facebook/mvfst@65b2973 commit

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-30403 updated 2026-06-28 cvss 7.3

mvfst: mvfst heap buffer overflow

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 15 mo ago (2025-07-11)

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	8.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
CNA	3.1	8.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Affected products

Facebook mvfst

References

Sources

CVE List CVE-2025-30403
NVD CVE-2025-30403

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary