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Vulnerability record · CVE-2019-11921 · published 25 July 2019

CVE-2019-11921: Facebook proxygen out-of-bounds write vulnerability

Facebook · Proxygen

An out of bounds write is possible via a specially crafted packet in certain configurations of Proxygen due to improper handling of Base64 when parsing malformed binary content in Structured HTTP Headers. This issue affects versions of proxygen prior to v2019.07.22.00.

9.8 CVSS 3.0 Critical EPSS 2.1% · top 19.3% CWE-787 · Out-of-bounds write
9.8CVSS 3.0 base score, v2 7.5
2.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

An out of bounds write is possible via a specially crafted packet in certain configurations of Proxygen due to improper handling of Base64 when parsing malformed binary content in Structured HTTP Headers. This issue affects versions of proxygen prior to v2019.07.22.00.

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

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

References

LinkTags
https://github.com/facebook/proxygen/commit/2f07985bef9fbae124cc63e5c0272e32da4fdaec PatchThird Party Advisory
https://www.facebook.com/security/advisories/cve-2019-11921 Third Party Advisory
https://github.com/facebook/proxygen/commit/2f07985bef9fbae124cc63e5c0272e32da4fdaec PatchThird Party Advisory
https://www.facebook.com/security/advisories/cve-2019-11921 Third Party 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-2019-11921), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.