CVE-2026-58055

nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length

Published Jun 28, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Description
nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8495-1 nghttp2 vulnerability
History
Type Values Removed Values Added
First Time appeared Redhat
Redhat hummingbird
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics threat_severity

None

threat_severity

Moderate

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.
Title nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length
First Time appeared Nghttp2
Nghttp2 nghttp2
Weaknesses CWE-444
CPEs cpe:2.3:a:nghttp2:nghttp2:*:*:*:*:*:*:*:*
Vendors & Products Nghttp2
Nghttp2 nghttp2
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:L/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Jun 29, 2026, 1:51 PM
Reserved
Jun 28, 2026, 12:55 AM
Status
Analyzed
Published
Jun 28, 2026, 2:16 AM
Modified
Oct 25, 2026, 5:10 PM
Severity
Moderate
Public date
Jun 28, 2026, 1:32 AM