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.
CVSS Details
- CVSS 4.0 Base Score: 6.3 (MEDIUM)
- CVSS 4.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)
- CVSS 3.1 Base Score: 5.4
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Redhat_linux | — | Upgrade nghttp2-debuginfoUpgrade libnghttp2-debuginfoUpgrade nghttp2No solution existsUpgrade nghttp2-debugsourceUpgrade libnghttp2Upgrade libnghttp2-devel | Jul 22, 2026 | Jun 28, 2026 |
| Rocky_linux | — | Upgrade nghttp2Upgrade nghttp2-debugsourceUpgrade libnghttp2-debuginfoUpgrade libnghttp2-develUpgrade nghttp2-debuginfoUpgrade libnghttp2 | Aug 17, 2026 | Aug 14, 2026 |
| Ubuntu | — | Upgrade nghttp2 | Jul 2, 2026 | Jul 2, 2026 |
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