Vulnerability Intelligence Report
nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length
CVE-2026-58055
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.
No Active Exploit Signals
CVSS Base Score
5.4
MEDIUM
Exploitability:2.3
Impact Score:2.8
EPSS Probability:0.20%
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
—
Authentication
—
Weaponization
—
SSVC Action
—
Weaknesses (CWE)
CWE-444 ↗Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| nghttp2 | nghttp2 | 0 <= 1.69.0 (affected) |
References & Technical Advisories
No reference links found.
Threat Intelligence Signals
EPSS Score
0.202%
GitHub Advisory
Identity & Timeline
| Status | PUBLISHED |
| Assigning Authority | VulnCheck · Bug Bounty Provider · USA |
| Reserved | 2026-06-28T00:55:25 |
| Published | 2026-06-28T01:32:57 |
| Patch Date | 2026-06-26 |
| Last Updated | 2026-06-29T13:51:59 |
Community Chatter & Buzz