CVE-2026-73550 Envoy - Denial of Service

Envoy < 1.36.10, 1.37.6, 1.38.4, and 1.39.1 contains a denial of service caused by improper handling of HTTP/2 Host header values and HPACK indexing, letting unauthenticated clients exhaust memory, exploit requires HTTP/2 HPACK and duplicate Host discard behavior.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
Proof of concept available
Authentication
Not required
EPSS
0.55% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
21 September 2026
Updated
15 October 2026
Weakness
CWE-401

Vendor fix

Update to versions 1.36.10, 1.37.6, 1.38.4, or 1.39.1 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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