CVE-2026-78660: high-severity vulnerability in Go standard library net/http
HTTP/2 transport accepts malformed framing-related headers 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%
Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing. However, this makes it possible for our HTTP/2 implementation to forward responses containing such headers to an HTTP/1 client when acting as a reverse proxy. If the HTTP/1 client also does not behave strictly enough, this can result in response smuggling.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Affected products
golang.org/x/net · golang.org/x/net/http2Go standard library · net/httpGo standard library · net/http/internal/http2Related 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%