CVE-2026-94439: high-severity vulnerability in Go standard library net/http
HTTP/1 server connection desynchronization after 2xx CONNECT response in net/http
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.4%
When an HTTP server handler sends a 2xx response to an HTTP/1 CONNECT request and returns without hijacking the connection, the server improperly continues to read and serve requests from the connection. Since a 2xx response to an HTTP/1 CONNECT converts the connection into a tunnel, the server should not treat the connection as continuing to contain HTTP. The impact of this misbehavior is mostly limited to potential request smuggling, where an intermediate proxy considers the data on the connection to be tunneled and the server considers it to be HTTP.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
Go standard library · net/httpRelated CVEs — Go standard library net/http
In the same product, most dangerous first.
CVE-2023-45288HIGHHTTP/2 CONTINUATION flood in net/httpEPSS 92.0%CVE-2022-41717—Excessive memory growth in net/http and golang.org/x/net/http2EPSS 6.1%CVE-2022-41723HIGHDenial of service via crafted HTTP/2 stream in net/http and golang.org/x/netEPSS 4.6%CVE-2023-39325—HTTP/2 rapid reset can cause excessive work in net/httpEPSS 3.8%CVE-2026-39821CRITICALInvoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idnaEPSS 1.8%CVE-2022-1705MEDIUMImproper sanitization of Transfer-Encoding headers in net/httpEPSS 1.5%