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Fencer Vulns
critical 9.8

CVE-2019-11940 json

In the course of decompressing HPACK inside the HTTP2 protocol, an unexpected sequence of header table resize operations can place the head…

published 2019-12-04 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-3596

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 71%
public exploits
0
none known

Summary

In the course of decompressing HPACK inside the HTTP2 protocol, an unexpected sequence of header table resize operations can place the header table into a corrupted state, leading to a use-after-free condition and undefined behavior. This issue affects Proxygen from v0.29.0 until v2017.04.03.00.

Patch / fix

Exploit prediction

1.36% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Facebook Proxygen

Classification

Weakness

References

Sources

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.