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Vulnerability record · CVE-2021-24029 · published 15 March 2021

CVE-2021-24029: Facebook mvfst vulnerability

Facebook · Mvfst

A packet of death scenario is possible in mvfst via a specially crafted message during a QUIC session, which causes a crash via a failed assertion. Per QUIC specification, this particular message should be treated as a connection error. This issue affects mvfst versions prior to commit a67083ff4b8dcbb7ee2839da6338032030d712b0 and proxygen versions prior to v2021.03.15.00.

7.5 CVSS 3.1 High EPSS 1.2% · top 33.4% CWE-617 · CWE-617
7.5CVSS 3.1 base score, v2 5.0
1.2%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

A packet of death scenario is possible in mvfst via a specially crafted message during a QUIC session, which causes a crash via a failed assertion. Per QUIC specification, this particular message should be treated as a connection error. This issue affects mvfst versions prior to commit a67083ff4b8dcbb7ee2839da6338032030d712b0 and proxygen versions prior to v2021.03.15.00.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/facebookincubator/mvfst/commit/a67083ff4b8dcbb7ee2839da6338032030d712b0 PatchThird Party Advisory
https://www.facebook.com/security/advisories/cve-2021-24029 Vendor Advisory
https://github.com/facebookincubator/mvfst/commit/a67083ff4b8dcbb7ee2839da6338032030d712b0 PatchThird Party Advisory
https://www.facebook.com/security/advisories/cve-2021-24029 Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-24029), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.