CVE-2026-58055
nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length
Vexday Risk Score
33Attention
SSVC decision (CISA)
Attend
PoC available → attend closely
CVSS 6.3EPSS 0.2%KEV nãoPoC públicaNuclei —Metasploit —Patch referenciado
Lifecycle
28 Jun 2026Published on NVD
Recommendation: Plan a near-term fix — a public PoC already exists.
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:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:L/SA:N
Affected products
nghttp2 · nghttp2public PoCs found — 1
cve_referencegithub.com/bikini/exploitarium/tree/main/nghttp2-nghttpx-upgrade-queue-poison-pocunverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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Talk to TrueHacking →References
https://github.com/bikini/exploitarium/tree/main/nghttp2-nghttpx-upgrade-queue-poison-pochttps://github.com/nghttp2/nghttp2/commit/ab28105c4a0197da24f8bfc414bc116055249e1ehttps://www.vulncheck.com/advisories/nghttp2-nghttpx-http-request-response-smuggling-via-upgrade-request-with-content-length